Thanks - Ok, will start taking the whole thing apart. A lot of aggro just for a syphon diaphragm.
Reckon I'll fit a service valve on the cistern feed wheat the same time - looking at other posts on this site it seems the double trap syphonics aren't the easiest to get right - I may be taking...
I have an Armitage Shanks syphonic WC (1970's vintage) which is becoming difficult to flush - I think the diaphragm in the syphon is faulty because the lever flaps around for a few goes before the flush kicks in (have tried increasing the water level in the cistern but doesn't fix it). I need to...