pppoffice
AudioBear
A thought, since there has been a bunch of soldering on wires... I would be VERY suspect of the shielded cables... the center wire insulator is almost a foam, if to much heat is used on the shield it can melt through and give you a nice short to ground, so maybe some passive ohm meter checks might be in order....
AND
I would ( when testing the 2513 ) see that you get signal on the input wires on the correct 2512 pins going into the 2507 , but do NOT have the 2507 in circuit.
I checked all of the shielded cables that go to the 2513 board and there are no shorts. I think that I had mentioned to you that I redid the red cable as the wires were getting all screwed up and could possibly short to each other and now i have also made the same kind of repairs to all of the shielded cables that go to the 2513 board.