Mackie ProFX12 V2 Request for schematics and repair knowledge

Hello, I am in the process of repairing the Mackie ProFX12 V2 mixer for a client, and am running into the unavailability of schematics. Does anyone have a copy they could share? I have already reached out to Mackie directly but am still waiting for a reply.

Additionally, I am having trouble identifying the failure mode for the two channels that have failed: one produces loud static (indicating bad op-amp or feedback resistor perhaps?) and the other has the right channel producing a 60hz hum, the other is functional. (see board photos, with the two failed channels being marked with "F". The browned area is residual flux from having replaced two opamps, and having reflowed other components around them)

Any help on either of these fronts would be invaluable. I have mainly worked in laptop and computer repair, and am just getting started with my first scope and first set of board level repairs.