So, thanks to the descriptions you all gave me of having to remount a
new toilet and thanks to the chance of saving money, I'm enquiring on if
I can repair the toilet I have. It's a Groco Type K, I can't find any
other numbers or model name other parts numbers on the handle and such.
Anyway, I took off the little backing plate on the back of the toilet
near the bottom with the water intake nipple. Under it is a flat piece
of rubber about 2"X3." It has a flap cut into the middle it with square
piece of flat metal attached to it. Is this the joker valve? The metal
piece contacts the internal portion of the foot pedal.

Just above the metal piece attached to the flat rubber is a tear in the
rubber. Should I fix this? How do I do so? Can I get a replacement part?
Does this make enough sense for anyone to have any ideas about what I
should do?

Thanks,

Stephen