I use 2N3055's as well. I usually buy them 10 at a time and gain match them when I get them.
When working on any of these amps, I leave the compensation diode loose from the clip until I'm done removing and replacing the boards, that way the leads will not be flexed any more than necessary. I worry more that the diode lead will break and causing the amp to go into meltdown mode.
I should have guessed that the outputs were mixed and matched from the description of the 24 volt regulator board!
I have nothing against NTE parts, but I hate to pay all that money for them when it isn't needed.