I have been using a MFJ-989C tuner for about (5) years without any problems.
Just recently I have noticed that on the higher band, 24 MHz that the SWR
occasionally would jump from an adjusted 1:1 SWR to infinity. A slight
adjustment of the roller inductance appeared to solve the problem although I
haven't ruled out a balum or antenna problem. I plan on investigating that
this weekend, however, before I open the cabinet and look for problems I
would ask the group for recommendations on cleaning the roller assembly and
inductor to ensure good conductivity after I am done.

I still have some old cleaning solutions from the old TV tuner days, some
electrical cleaner (Appears heavy duty stuff) but maybe there is some other
solutions someone might recommend.

Your thoughts and recommendations are appreciated

Ron - W4LDE