As another possible debug method, are you able to plug an external speaker into the "EXT SPKR" jack on the back:
1. This could eliminate the possibility of a bad on-board speaker?
2. The jack actually acts as a switch to disable the on-board speaker (when an external speaker is plugged in). If the jack-switch is bad, it would match some of the symptoms.
Note: If the headphone jack is bad, it too might result in the internal speaker being disabled. I'm not convinced either of these is true (because you hear an initial pop), but might be worth trying to eliminate.
Have you turned the APF on/off? Note the different paths below.?
Just some thoughts ...
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-Mat Breton, N8TW
Mat Breton N8TW