So, Dad (me) goes to empty the cassette for the loo. "Don't use the loo" Dad tells the kids. "We won't" chorus the kids in unison. Dad returns five minutes later to find the cassette cupboard for the loo has a generous helping of yellowy liquid in the bottom of it. "Sorry Dad I forgot" says 5 year old son (it's amazing how much can come out of a 5 year old.......) Anyway, the point of all this is that when the cassette is removed the black flap thing to let the contents out of the loo can't be opened - so does this mean that the seal on mine has had it, or are they never that good? I really do need it to seal, the kids won't always remember no matter how much I tell them! The cassette itself seems OK, a tiny dribble sometimes from the main valve when carrying it. I'd offer money that it's never been serviced, it's 9 years old, is it worth (and can you get) a service kit for the lovely job of changing the seals?