C2 is not polarized, so it shouldn't matter how it is inserted into the board.
Does your meter have a diode test setting? If it does use it to check for continuity from the output transistor cases to the chassis. If the transistors are not connected to the rest of the circuit, there will be no reading between the case and the chassis. If the red wires are connected to the transistors, there will be a slowly rising reading as the filter caps will be charged by the meter battery.
No matter what, there should not be a steady zero ohm reading from the case to the chassis.
Steve, if you are going to walk him through this repair, I will defer to you. He is getting too many instructions to follow and he is bound to get mixed messages from too many of us.