I have recently purchased a Marantz 2220B as-is, fully expecting it wouldn’t be fully operational. I’ve done some basic service on amplifiers before so I figured it wouldn’t be too difficult a task to try and get this one going, but my limited knowledge and experience has unfortunately left me stumped on the most significant issue. I cleaned it up so I could visually inspect for any obvious component failures, hooked up some sacrificial speakers, and powered it up. I found the right channel operates as-expected, but the left channel produces a loud crackling that is completely unaffected by the controls - changing the input, or adjusting the volume and balance does nothing to affect this noise, but the audio underneath is still present. Since it’s only affecting one channel, it seems logical that the fault isn’t in the power supply, and as it’s unaffected by controls, led me to believe the fault is in the power amplifier. Initially, I thought it might be an issue with the output transistors, but I pulled and tested them with a multimeter and they seemed fine. I then checked the bias on the outputs using the locations posted in the service manual correction thread, and both channels were out of spec, with the left moreso. I adjusted the right, but the left channel wasn't giving me solid readings while trying to dial it in, so I’ve put that off for now assuming that the bias issue in that channel are largely another symptom of the primary fault I've yet to ascertain. Any ideas what I should be focusing on at this point? I thought it may be an issue of bad capacitors due to the unit's age, so I ordered the requisite components for a recap, but I don’t know if they would cause this sort of issue without any immediately noticeable signs of failure on the main amplifier board.