[Kenwood] TS-850 erratic tuning

[Richard Ferch]

At a certain point in the tuning knob rotation on my TS-850, tuning
sometimes becomes erratic. Turning the knob slowly seems not to change the
frequency at all, and turning it quickly can sometimes result in the
frequency jumping in the opposite direction by a couple of kHz. This
happens, if and when it does (wouldn't you know it, it's behaving fine right
now), at a certain point in the knob's rotation, not at any particular
frequency. I'm wondering whether there is dirt in the encoder, or something
more serious. Is this a user-maintainable part, or do I have to replace the
encoder (or have it replaced)? Has anyone seen this before?

73,
Rich VE3IAY