A friend of mine owns two Sony tuners, a 730ES and a 222ES.
After prolonged periods of storage, the AM stepping has changed to 12 kHz.

I have the maintenance manual on the 730ES, and there is no mention of a
method of setting the AM stepping, and there are no DIP switches in the
unit.

There aren't any switches in the 222ES either, which has a lithium battery.
The battery was dead when I originally obtained the unit, but this problem
did not result.

How to fix?