Erratic Dometic fridge on gas

This fridge... a Dometic RM7271 in an 2006 A/S Inca... chilling nicely on 12v, 240v, and gas... so long as it stays lit. 
It'll usual light nicely, in that it lets out a few rapid clicks from the ignitor and a little "poof" of the burner lighting, and can stay like that for anywhere between a few minutes to a few hours. Then it'll start rapidly clicking the ignitor again, suggesting the flame has either failed or there are insufficient messages getting to the main gas valve. Turning the three-way control to off then back on again usually (but not always) sets it right, but only temporarily.
I found some interesting advice on a similar topic on the forum... https://www.autosleeper-ownersforum.com/t38217-dometic-fridge-not-working-on-gas-or-240v
and wondered if my problem might be similar, and also wonder how the situation panned-out for the OP. 
Some interesting advice was given regarding stripping down the control panel, cleaning connections, and overhauling the 3-way switch, with some sensible advice to get the fridge serviced first anyway.
Here in the western edge of Cumbria, since my regular guy let his gas ticket lapse, the nearest service depot is Bardsea Leisure in Ulverston, which must be the best part of a 2 hour drive away from me. The soonest  they can look at it is late August and I'd have to stay in their campsite while they play with the fridge. I can see a scenario where they fail to replicate this erratic fault, and/or (at my expense) fail to fix it by changing jet/burner/ignitor/thermocouple/gas valve etc.

Some thoughts on the most likely causes and fixes would be most welcome.

I would suggest you first look inside the gas working part of the fridge. They normally produce a lot of rust dust which falls down on to the burner, and you could have the situation where it is on the cusp of working  / not working. Take the lower vent panel off and look at the burner parts at the bottom left of the back of the fridge. You can see one or two Pozi screws you can undo to inspect what's going on inside the tin can that shrouds the burner flame. If you see rust dust there, hoover it all out. With the burner exposed, light it via the sparky and see if you get a flame about 1/2 inch high, or a bit higher. Make sure the flame isn't going to burn anything of course, but that is unlikely as there isn't anything flammable in the vicinity. If the flame is weak or small, or yellow then your action needs to be either buy a new burner assembly, or dismantle it and clean it out.
You are allowed to work on gas appliances on your own vehicle, but not on other peoples'. The logic is that you are allowed to change your gas bottle, which has as much chance of you doing something wrong as does dismantling your fridge burner. That is why it is legal to work on your own stuff. But not on other people's, unless you are registered.

gassygassy wrote:I would suggest you first look inside the gas working part of the fridge. They normally produce a lot of rust dust which falls down on to the burner, and you could have the situation where it is on the cusp of working  / not working. Take the lower vent panel off and look at the burner parts at the bottom left of the back of the fridge. You can see one or two Pozi screws you can undo to inspect what's going on inside the tin can that shrouds the burner flame. If you see rust dust there, hoover it all out. With the burner exposed, light it via the sparky and see if you get a flame about 1/2 inch high, or a bit higher. Make sure the flame isn't going to burn anything of course, but that is unlikely as there isn't anything flammable in the vicinity. If the flame is weak or small, or yellow then your action needs to be either buy a new burner assembly, or dismantle it and clean it out.
You are allowed to work on gas appliances on your own vehicle, but not on other peoples'. The logic is that you are allowed to change your gas bottle, which has as much chance of you doing something wrong as does dismantling your fridge burner. That is why it is legal to work on your own stuff. But not on other people's, unless you are registered.

Wise council gassygassy... checking the simple stuff first. 
Will try to dodge the raindrops over the next few days and have a look. My last A/S van, you had to completely remove the fridge from the van to get to the burner. Am hoping this particular installation provides much better in-situ access.

Sods Law seems to have kicked in. 
Ever since I started this topic, I have had the fridge running on gas and it has behaved immaculately. It hasn't once done any of the clickety-clicking of the ignitor I've mentioned. It runs perfectly, and I've tried turning it off then back on again and it relights perfectly and stays lit.
I took the lower grill off to see what I could see, and finding the burner assembly and shield too far down and to the right to allow access for dismantling, could only inspect. With a black cagoule over my head to block out the bright sunlight and squinting at an oblique down and right, I could just about make out a blue flame with the igniter glowing in the upper part of the approx half inch flame. I could see the white porcelain barrel of the flame-failure sensor pointing towards the lower half of the blue flame, but couldn't get a view of its end, or where it might be in the flame.
I really don't want to take the fridge out, especially as I don't have the means to bench test it, so the only thing I can think of doing is blasting the burner, by lung power, with a piece of plastic tube directed vaguely at the burner. But as the flame is blue, with no orange or yellowing that might result from crud fallen onto the burner, I suspect that would be a waste of time.
What a pain intermittent faults are!

I was just going to post my reply when I saw your latest. Good to know it is now working. There wasn't any cobwebs in the vent when you removed it was there? I have known in the past of cobwebs preventing enough air getting to a burner causing it to cut out.
Anyway you have seen what it should look like, so if it goes wrong again you will at least have the confidence to tackle it.
 I got the burner position wrong in my last post, I don't know why I said left!
Your Inca looks the same inside as my Pollensa except that the seating arrangement is on the opposite sides to mine. I have one long single bed sofa and the two facing two-seater sofas make into another bed. This leaves the central aisle free so you don't need to climb over someone else to get up. We have this arrangement in our Bourton as well, and it is the reason we went for the Pollensa, as well as the fact that our Pollensa is on a Ford Transit automatic. That is what I wanted. We will sell the Bourton in due course and keep the Pollensa.

I really don't know if this intermittent fault has been cured gassygassy. But as it was still running perfectly this morning, I decided there was nothing to be gained by tinkering with it any further so I shut it off and will be keeping fingers crossed for our next trip off-grid.
However, one piece of information I did find that might be relevant... good old youtube... was that the gas valve is notorious for sticking, especially after a winter layover. This particular youtube recommended placing the chuck of a battery-powered hammer drill against the gas valve and giving it a rattle on hammer mode to free up the sticking valve. It apparently cured his same problem... no sustained ignition, flashing gas LED, and manically clicking igniter. Have you heard of this fault and cure?
I doubt I'll go to the extreme lengths of carrying a fully-charged hammer drill in the van at all times... just in case... so hope that an 8oz hammer rattling against a metal rod might almost replicate the hammer-drill. I'll have to see.

Interesting that you should mention lounge/bed layouts though. We got our Inca last year for the sole reason it had an end lounge, enabling free run of the entire van when the bed is out. What we hadn't thoroughly investigated though was the relative complexity of converting the j-shaped lounge into a double bed. After a long day, nodding-off to a late-night movie after a couple of glasses, the last thing you want is 2 adults indulging in 3 minutes of calisthenic work-out. How come it is never as easy as "pull this out, flip that over, and jobs a good-un"? I have yet to see an A/S van that solves this problem. I think I'll investigate to see if other posters have discussed the various A/S bed/lounge options and relative convenience of conversion. Maybe even start another topic.

Yes, you could have a sticky gas valve, if it hasn't been operated for a while. You don't need a pneumatic jack hammer, if you can reach it easily with a stick or rod of some sort just give it a tap. In any case a hammer drill doesn't do any hammering unless its drill bit has pressure applied to it so that idea sounds clickbaitey.

As for the layouts, I looked on line at an Inca and found it was the same layout as ours. You must have a different Inca. The specific reason we like the layout we have got is that although you do have to make up one bed at night, there is always one single bed available in the day, secondly that you don't have to lift a heavy bed base to get at the bedding when you are tired.We just chuck it all with gay abandon into the over-cab loft area. We have two two-seater sofas facing each other with the table in between, which still leaves the gangway open through the whole length of the van, and we don't have to swivel the front seats to make any lounge seating.
Making my bed is thus:
1) Pull one two seater sofa forwards and tuck its backrest in the gap.
2) Pull the other two seater sofa forwards and tuck its bacrest in the gap.
3) stick the two infill square section bits at the end
4) Drag the bedding down from the loft and chuck it on the resultant6ft 6ins x 4ft 6ins  single bed.

A better, alternative method is this:
I get undressed and chuck my clothes on to the fridge worktop area and go into the washroom and have a wash and brush-up.
Meanwhile, Mrs Wifey goes through the procedure listed above.
I exit the washroom nicely refreshed and get into my bed that wifey has made. Hers is permanently made, anyone who wants to can have a quiet nap there during the day.
Simple. But then, in the morning I get her a cup of tea in bed. Fair exchange of labour if you ask me.