Can you part replace IDeal Standard Whisper Cistern inlet valve Drainage and wastage systems and plumbing help, advice and answers

[svwhat]

HELP ! I have old style Ideal Standard WHISPER inlet valve with threaded nut that is leaking so toilet constantly overflows.
Been told 30mm DIAPHRAGM was discontinued and cannot find stock anywhere.
I know I could replace the WHOLE valve with new, but my new house builders thought it a good idea to tile in the whole area around the cistern so cannot access bottom of valve to replace without removing a lot of tiles !!!!

Is there an option to part replace the top of the valve assembly with something that would fit .

I see an inverted plastic nut near top of valve but would need same sized top structure to replace the whole.
I presume everything is 1 1/4 inch

Any ideas thank you and the plastic nut appears very hard to undo as the whole pipe turns whilst I try to unscrew . AGH this is a real pain

Thanks
simon

[lets have a look]

Welcome to a plumbers world where everything has to be boxed in and tiled over, a picture would be good, if i struggle to get a part I always go to BBS bristol building supplies,try online or a phone call,just got a new b/valve washer for the same problem as you have that no one else could identify it

[svwhat]

Thank you. Hopefully problem solved. Bought a few wrenches and undid the plastic nut and able to take off top of valve housIng diaphragm. Old diaphragm seemed to be glued in. Destroyed it trying to get out. Tried my luck and popped in new diaphragm supposedly for new valve design and it fitted. Just screwed it all up and hey presto it worked. Oh and replaced push button assembly as well and that works better than original . Will buy more spares for next 20 years of happy flushing now I know how to thanks