My toilet has experienced a sudden failure to flush. The cistern is full and depressing the lever is causing the rod in the flush mechanism to be elevated but the water is not released in the normal manner. Don't know the manufacturer of the flush for sure but the bowl is made by Trent.

Jonathan Brearley, July 2008

From your description I gather that your cistern has the siphon type of mechanism that has a semi-rigid membrane over a plastic grid inside the siphon which lifts the water past the top of the siphon and the rest of the water keeps flowing through the siphon past the lifted semi-rigid membrane, to complete the flush. With use this membrane might have been torn and is not doing its job. Be bold, remove the siphon and put a new membrane. Mine worked for a long time now. If the siphon cannot be dismantled without damage you might as well purchase a new siphon. Hope this works. Good luck.

DIYer A.V., July 2008