I need some extra eyes (brain cells would help too) looking at this problem.....
What "we" know - the amp will power on and not blow fuse(s) - you can chase a signal from Q1 (NPN) to Q2 (PNP) but there is no signal at the collector of Q2. When checking the supply voltages I get a +15/+9 and -15/-3.5 - checking the 9V zener diode (ZD5) and it is okay. When I lift R63 on the -9V supply I get -9V at ZD5 - someting is loading down the supply - but what? I checked Q2 through Q5 with a DMM in circuit and found no issues. D1 and D2 (are these bias diodes helping the BJT turn on??) also test good and the ESR on all the bypass caps (C8,12,20) all test out okay. Check the voltages on Q2 - Q5 but they have to be wrong since the -9V supply line is pulled down. I hate to start removing parts without a strategy.......