I have an old Kohler shower diverter valve that is stuck. After removing the bonnet nut I found what looks to be a floating sleeve holding the diverter valve in. Any suggestions how to free up the sleeve without damaging the stem or housing? Could I just unscrew it part way and give it a few good wacks into the valve to loosen it or will this damage something? I have removed the hot and cold water compression valves with no problem.