Quote Originally Posted by jsmabrey View Post
Can the Kohler Cartridge #78913 be repaired by a DIYer? The valve stem has only 1/4 rotation with the limit stop removed. Therefore the shower produces only hot and hotter flow. The supply of both hot and cold is within specs. The inlet check/stop valves are open.

A new cartridge is about $200 which I would like to avoid with a in-house repair. Any advise?
I have two of the same mixers, both failed to adjust from full hot. Rather than pay for two new valves I have taken each one out and soaked them in CLR for an hour, rinsed and re installed, both work fine. I have had to do this twice a year for the four years I have lived here to clean out the calcium buildup even though I have a water softener. I remove the screens and o rings first then soak the metal parts in a glass mug then rinse and lube the o rings with silicone grease, re adjust the temp limits and we are back to happy until they get stuck again. Hope this helps.