[Drake] Need advice - R-4C Passband Tuning askew

[W7DAH]

I have an R-4C that has been setting on the shelf, unused for some time and
the Passband Tuning seems offset hard to the right now. LSB signals require
the dial to be set right of the 12-o-clock position, halfway between the
12-0-clock position and "USB" even on 40 & 80M ... Actual USB signals require
FULL clockwise rotation, beyond "USB". What are the prime suspects, where
should I start in order to tweak things back to normal, please?

Thx
--
Don - W7DAH
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