Tom, you mentioned having another supply.  Hook that one up for a while to 
see if the problem appears again.  If so, its not the same supply.  Then 
swap out each jumper switch and tuner in the same way.
I don't know anything about the tentec tuner.
I have an MFJ 989 with a big roller inductor.
Every few years I have to clean the roller and the shaft it sits on.
Lots of contact cleaner for the job.

H T Kaufman MSW LCSW
Adaptive Technology Instructor