<< what is best way to repair? >>
1) Call Kohler customer service. They are tops IMO.
2) Request a parts list for your toilet.
3) Order the needed parts (you may ask for help on this, they are pretty good
at suggesting remedies)
4) Install parts.
5) Pat yourself on the back for reducing your water bill a bunch.
6) Keep this telephone number handy: 1800 456 4537 in case you need help later.
7) Call 1800 433 6287 for literature to inspire your next remodeling project,
kitchen, bath, whatever.