you will have to open it up and take a look around. follow the schematic and see if the parts are still connected and look in good working order. to get into it you ll need to remove the 8 screws in its back.
Then, remove the out Jack and the amp board which is held in place by the 4 knobs of the front panel. Then use a multimeter and do some measuring.
I’d start with the 1K resistor right at the jack. If you are unsure, you can always add some pictures to your question so we can see what you see. Voeg afbeeldingen toe aan een bestaande vraag