we have a thetford c4 toilet in our caravan which when you come to empty it allways has overspill on the cassette itself and in the handle recess, have changed the seal but its still the same the van is 15 years old ,could the whole unit be ready for a change or is there a simple solution to the problem any advice much appreciated ..thanks MR D BINCH

MR DAVID BINCH, June 2011

go to thetford website downloads free pdf's then also send thetford the question as to what could be causing tell them you've changed the seal but problem still exists then may come up with a different solution. I woldn't have though it needed to be replaced I've had caravans that old and mine were ok just needing the odd seal and pump.
One though on the cassette is the air control for emptying lets air in the seal may need replacing on that just check out the pdf's first.

Bob, June 2011