Did you try it with a battery again? Also, open it up and see if there are any loose wires or something smells burned.

So you plugged a power supply in that had reversed polarity?

http://electroharmonix.vintageusaguitars.com/index.php?option=com_content&view=article&id=23:the-eh-acoustic-guitars-pt-1-the-e-h-guitar&catid=13:electro-harmonix-articles&Itemid=45

Your pedal probably has splined shafts on the pots. I’m not sure if the pointer knobs are available in that format.

I can’t answer your 1st question without taking a look at mine but I can help with the other 2. The switch is likely just pushed in. If you look inside the pedal, you can usually see the bottom of the switch coming out of the tabs that hold it in. You can just push it back up and bend the tabs in a little tighter. There’s a small metal piece inside the switch that makes the contacts so if the switch is completely apart, that piece may be floating around inside.
For the led, it’s easy to replace. Just keep track of which wire goes to the flat edge of the led.

12″ 8 ohm 75w speaker. 50oz magnet and 1.75″ voice coil

Plug your synth into an amp. Take the speaker out jack of the amp and plug it into the amplifier jack on the Golden Throat. The speaker out of the Golden Throat has to connect to a speaker, not a line in jack. The red light will only light up during overload conditions.

It has to have a speaker level output so you’ll have to run it through an amp first.