Cistern doesn't empty fully on flushing

[edwardxpx]

I am having a little trouble with my loo - when one flushes, only about a quarter of the water in the cistern is delivered into the bowl. I can get all the water in by flushing repeatedly. But a single flush doesn't deliver it.

Might something be wearing out such that a good delivery of water from the cistern to bowl isn't happening? It's all fairly moden and conventional in the cistern - plastic plumbing fittings, low level cistern.

 

[ChrisR]

Sounds like only the first part of a "double flush" unit is working. Can you take pics of the inside of the cistern?

 

[edwardxpx]

I think I have the answer - from some research it sounds like a split or damaged siphon diaphragm. I have a 2 part siphon so it looks like an easy job. Thanks for your interest.