Top lockers dropping WXL

The run of three top lockers on the driver's side of my WXL is dropping away from the roof at the rear of the van, this is resulting in the cupboard doors twisting slightly and sticking, with the catches of the two rearmost cupboards not always catching properly.

I have checked the screws underneath the cupboards and these are all fine and tight. There are two screws holding the top trim panel to the ceiling of the van. The one nearest the wardrobe is fine, the one nearest the back doors is loose, I have tried tightening it and coating with glue then tightening, neither has made any difference.

I feel that I want to add more screws to secure the top of the cupboards but don't know what is immediately above them, I don't want to put a longer screw in and pierce a hole in the outside skin. Alternatively I could try same length but wider guage screws.

Does anyone know what is immediately above the roof panel where the screws for the overhead lockers are attached?

Thanks in advance.

I had a similar problem that was cured by additional screws, I seem to recall there are some screws just behind the hinge inside the lockers I put additional ones in here and an additional screw in front of the cupboards in the strip of wood on the ceiling. I went with the same length that was already fitted. You would be best go prop the cupboards into the correct position before fitting new screws. 
If you need more info let me know as I’ll have access to our van during next week and can take some pictures. My fix has held for about three years now.

That is helpful, thanks. I hadn't spotted screws inside the cupboards. Van is in at dealers just now having warranty repair on Truma system, I hope to get it back early next week the will have a good look and have a go with more confidence than I had not knowing if more screws were possible.

Mine went back to the dealer to fix the cupboards problem which they failed to do, the usual we’ve had a go at it, see how you get on. Hope it works out for you

Just this morning I have rescrewed the microwave cupboard to the roof , it was starting with a little gap,  I removed the screw and inserted cocktail sticks soaked in wood glue in to the hole, I found a screw the same length but with a course thread and re screwed this in to the roof,  it’s now rock solid

Collected van from dealer at lunchtime, Truma system fixed under warranty. Have now had a go at screws on top lockers as described above... Cocktail sticks and wood glue. Looks much better.

Thanks for the advice. Finally should be able to book a few nights away this week now heating and hot water working, not that heating will be needed this week

Having spotted this thread earlier today I thought I would check our 5 year old Warwick XL.. Surprised to find that as per the original post, on the drivers side, the overhead lockers had dropped about half an inch at the rear and were surprisingly unsupported. The fastenings under the cupboard assembly seemed to be doing very little and are impossible to tighten due to the pelmet being in the way and the whole thing moved up and down very easily. Using some plastic storage boxes and an assortment of wood from the garage I managed to lift and prop the assembly to where it had originally been. I have now fitted a total of fourteen extra screws into the assembly, same size as the original ones near the hinges, some in line with those near the hinges upwards into the roof and some inside the base of the cupboards into the wall. It is now sturdy again. I would suggest the original fixings were less than adequate, but all is well now and so pleased that I saw this thread ..