ive never had one of these apart but the round piece that turns when flushed is not turning. It’s free and can be turned by hand but it doesn’t move when the peddle is pushed to flush. I took the peddle cover off and see the water valve but I’m stumped.
Round piece that turns? The big clam shell door in the bottom of the bowl? If so, the shell has cracked on the shaft end. Domestic, who now owns Tetford-Sealand, has the IPB and manuals on their web site.
If you have never worked on these heads, your time has come. Not to bad of a job if you can get the base band off.
Sounds like it is indeed cracked. Weird because in all these years I never had to replace the actual ball valve. The seal, yes... but not the valve.
I have replaced the whole assembly myself. I bought the kit which includes everything you will need. Make sure you pump out and flush the holding tank. I watched a youtube video and it actually very simple.