Speaking of the Icom 735
 

The common tuning encoder problem, where you spin the VFO
knob, but the frequency changes randomly are jumps around-
Icom no longer sells the encoder assembly, which was their
recommended "fix."
I've had the encoder apart and looked at the diagram,
but haven't gone any further. Looks like if the resistors
that feed the optos drift off value, it would hose up
the encoder. Has anyone else addressed this problem
at component level? Thanks, D.S.