We have a fairly modern Gala toilet. It's not leaking, but there seems to be a constant trickle of water into the bowl (abut the same amount of water as a dripping tap). I want to remove the cistern cover, but can't get it of! It doesn't lift off and there is a lot of resistance. I've considered just giving it a big yank, but will I damage it if I do that? Anyone else have/seen one of these? Also, any ideas about what to do about the trickle?