[Premium-Rx] WJ-8711A Help Sought

[W2HX]

Hi friends,

A few years ago, I picked up two WJ-8711A receivers. One looked nice in a desktop cabinet and the other was clearly a parts mule.

Nice one:
https://w2hx.com/x/Watkins%20Johnson/WJ-8711A/0423201757.jpg

Both units with the parts mule atop the nice one that is out of its nice cabinet
https://w2hx.com/x/Watkins%20Johnson/WJ-8711A/0423201903a.jpg

The nice one has some problems. BATT ERROR (no big deal, probably the coin cell needs replacing) and ERROR=11520
Any idea what ERROR=11520 is?  But probably worse, or maybe related, is an awful squeal coming out of the speaker..
https://youtu.be/aVI5blTALZM

Here are some internal pictures of the nice one.
https://w2hx.com/x/Watkins%20Johnson/WJ-8711A/0423201848.jpg
https://w2hx.com/x/Watkins%20Johnson/WJ-8711A/0423201850.jpg
https://w2hx.com/x/Watkins%20Johnson/WJ-8711A/0423201850a.jpg

Along with the parts mule, I also have tons of other parts including a spare board.
https://w2hx.com/x/Watkins%20Johnson/WJ-8711A/0423201850b.jpg
https://w2hx.com/x/Watkins%20Johnson/WJ-8711A/0423201852.jpg
https://w2hx.com/x/Watkins%20Johnson/WJ-8711A/0423201853a.jpg

interesting that the spare board uses a dallas cheerleader memory chip, whereas the nice one has some other chip in there (maybe EEPROM?).

some heavy encoder knobs and little panel switches (the current knob is garbage, so light)
https://w2hx.com/x/Watkins%20Johnson/WJ-8711A/0423201855a.jpg

Then here is the inside of the parts mule:
https://w2hx.com/x/Watkins%20Johnson/WJ-8711A/0423201907.jpg

This project may be more than I care to take on, but I figure with a parts mule, extra digital board, other various bits and bytes, I might be able to make one working radio. So my question to the group is, anyone have a suggestion on the audio howl/squeal? And what should I know about that error?

Thanks all!
73 Eugene W2HX