The spill was the reason the client sent the machine to me, but I also found several major cracks in the Bottom PCB. Not sure if these cracks occurred during shipping or were already present — perhaps the client didn't know because the spill was preventing tapes from playing anyway.

After adhering the cracked parts of the PCB back together, I installed a bunch of jumper wires to bridge all the parts of the circuit that were disturbed by the crack.