?

I have a different primary rig, but often dig my 857 out of it's storage box under my desk to play with it, learn it, and plan how to use it better. When I put it away some months ago, everything was Fine. But when I hooked it up yesterday to test with an ATAS, it wasn't as Fine as it was before the last nap.
I soon noticed that the last digit of the frequency display was stuck on "7".
So, when I spin the dial like this: 14 . 300 . 17 all digits move as directed except for the trailing 7. This means I cannot got directly on frequency, ever, and often SSB voices are just a bit more donald duck than they should be. Maddening.
I tried changing Menu 82 SSB step to change the tuning steps, but no real help here.

Suggestions welcomed, please. I will send it to repair if I have to, but would like one shot at fixing it myself. I'm not a competent tech, but can probably work through easy stuff.
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73, Charlie
WB4FAW
Colorado