My RCK60-29B mower that's installed on my B2620 HSD tractor seems to have a mind of its own. The height setting keeps slipping from the setting I choose and bottoms out to whatever setting the scalp wheels are set on. So far, 2 height cams, the height control rod and knob and the mower lift arm have all been replaced. The "fixes" are very short lived before the problem reoccurs. What's the fix and/or is there some way to permanently set the mower height at a given setting(approx. 3.5 on the mower knob)??