www.thetford-europe.com they may help but don't hold your breath for a reply.
If the old bench type then it's a C3 with electric valve sounds like the switch is stuck open.
sorry not worked on them. When you enter the site click on permanent toilets select your model.
If it's the older C3 bench type then I have a drawing if you want a copy e-mail me robertwhiting76@hotmail.com
Nobby
February 2009
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