I've replaced the siphon valve on our loo. Whilst I was at it I also replaced the doughnut seal as well (as recommended). I put it all back together again but the blasted thing is leaking - not by much, its just a small drip which seems to come from the underside of cistern and rolls down the pipe connecting it to the pan, and thence onto the carpet.
So, I have a loo that flushes, but now it leaks a bit. Great :-(
Am not a DIY expert at all (treat me gently chaps), so I am all out of ideas. Having managed to sort out the main problem, am maddened by the niggling little leak that has popped up.