I think one of the problems with these amps ( like with plenty of other equipment), is that they don't react well to electrical fluctuations/surges. I've now seen a couple that have failed when being used on stages, where the supply has been provided via a generator.
I attempted to repair one of these for a customer but without success. I couldn't get parts or even a schematic. As @BassBunnysaid, Real Electronics are the only real viable option. I came to the same conclusion as you, in that, it's not worth it.
Our IT team are tracking them down at this very moment. The highly trained BC stealth commando unit, have had Christmas leave cancelled and are on standby.
That's not good then. If you know what you're doing and can clamp the neck to get it straight, you might then have more of a chance at getting the truss rod nut loosened.