1999 Symbol Thetford C2 Cassette Leak

Hi there. I have a fluid leak from around the yellow button within the Vent Plunger. The fact that there are alignment arrows on the plunger unit and the cassette case suggests that the plunger unit can be removed to investigate the problem ? But I cannot see how to remove this. Any help would be much appreciated. I attach a couple of photos to show the problem. Keep safe and keep well.[You must be registered and logged in to see this link.][/url][/url]

If you push down the button and put a piece of wood (or even a spanner) across the button to use the raised shoulders as a lever and twist , if that makes sense.

Thanks Paul - can always rely on you to help out . I wished you lived nearby. So, one more stupid question - turn clockwise or anticlockwise ?

I think anti to undo and clockwise to replace. I haven't done that valve but it was similar procedure for the main seal.

Thanks to advice from Paul I was able to remove the old Vent Plug and decided to replace it with a complete new unit. Bought from Leisureshopdirect.com (their part number 229416) at a cost of 12.02 plus 3.99 postage. May get cheaper elsewhere but I have used this supplier before and am confident they provide genuine spares. Fitted this morning and all now seems good 

Thanks for the feedback Rob.

I wish everyone would do the same as it could be very useful information for others with a similar problem . . . like me, for instance.

Mine leaks a bit from time to time, so with your and Paul's advice it may well get fixed next time it plays up!