Hi Adam,
I have exactly the same issue, bought a new capacitor but I got one from Maplins for £5 instead of £20 via Saniflo. BUT it was too big. I just managed to get the housing closed and fit the membrane back on (mines a Sanitop) with a bit of silcone bath sealant but after a few days the fuse went caused by water that had got in. I have now ordered the right capacitor and have asked what to use to seal it and the local plumbers suggested "Plumba" which is a silcone sealant. Perhaps try "Hermetite Instant gasket" but you do have to use something as there was a trace of sealant on the plastic when I removed it. Good luck, be interested to know what you use and if it works. Nick
Nick Brotherton, January 2010