I got this repair on the bench today, and the PN2907 did not survive being installed backwards and was shorted out, and this pretty much tanked that half of the small PC board up front. One LED on the 9 pin socket was open also. The LED problem and some other soldering related issues look to be from using an iron that's not hot enough to properly flow out the solder quickly.
Fixing up the front PC board, I was then left with one dead channel and one half of your rear PC board that just wasn't passing any current. When I unscrewed your rear board and moved it, all of the wires broke in a way that's consistent with using a wire stripper on too small of a setting, which will cut into the solid core wire and weaken it so it snaps off. When I went to work replacing these, I discovered that all of the wire ends going to the terminal strips were just resting on the terminal strips with some solder, not passing through the terminal strip holes themselves, so I had to replace every wire required for Speedball installation because connections like those are likely to pop loose later on their own.
After installing all of the new wires, there was also some distortion in the previously working channel which I tracked down to a damaged transistor on the other side of the large PC board.
With all of those issues addressed, this amp is now up and running.
