The components and voltages are probably fine, if you remove the 68k resistor from the circuit and it will read 68k. Because you can wiggle the power cord or torque the chassis and have the circuit become intermittent, it would indicate that you have a loose or shorting connection. Use the chop stick method (carefully) to tap and push around on the components and leads to try and isolate the problem. Usually, it will reveal itself, that’s what a tech would do. From your description, it sounds like a weak ground or there is something amiss in the output impedance wiring.

BTW, a current limiter should be used while you work with the amp turned on to ensure there is not a dead short. There are a number of web pages explaining how to construct one, I think there is a link somewhere in the TAN forums. They are simple, cheap and easy to build. I built mine from parts I had in the garage. It sounds like you are very close to having the amp sorted out.