Domestic 110&210 Traveler Lite toilet

[Slownsy]

We have a problem with part 7 (ball,shaft & cart) the ball will return to far after release of pedal, if replacing kit Part 7 will this fix problem, or will I also have to replace kit 10 spring cartridge? Any help Much appreciated.
Frank.

[Slownsy]

Apparently no one works on toilet. Will have to pull apart and see what I can figure out.