Hi!
Wolfburg West in the USA do these also, not too sure how cheap it would work out at mind...
Mine leak also, but until i get round to fixing, i cram a cloth in the bottom, and just wring it out every so often - lord knows what my floor is like. My poor camper had a nice life in California, and ever since he came here it's been rain rain rain.....
As Rich said, it can take a long while, i wonder if boiling up the old seal would rejuvinate it? Sure someone mentioned this to me once????
Alistair