the fresh water tank in our Burstner, has a very small leak around the large red inspection cap, which is on the side of the water tank. There is a foam washer/seal that doesn't seem to want to seal it. It releases a small bead of water which can then drop down onto the van floor. Have taken the red cap off and re-seated the foam seal and replaced several times, but with no joy. The dealer did put a new seal in, which did work initially, but then after a couple of days, the inevitable drip re-appeared. Firstly, is there a better type of seal to use rather than a foam one? If so has anyone tried one? Where can I get spare seals from. Looked on the South Downs on-line shop site, but don't see one listed. This is not a major problem, but just one of those simple but annoying issues that just can drive you round the bend! Anyone else experienced the same problem?