Your problem sounds like a problem I had with an Intek. My problem was something in the circuit that protects the output transistors from harm in case of a short circuit. The circuit basically acts like a fuse, and shuts the power off to the transistors. To reset, you turn the amp off and wait a minute or two, and then turn back on. Well, my problem was that the protection circuit tripped for no reason whatever. I'd get that bang (more like a really loud pop for me) when I'd turn the amp off. I think the cirucit reset, and the power stored in the capacitors would rush into the output transistors....
I still have the Intek, although I don't use it now. Sometimes I can persuade it work by turning it on and letting it warm up a long time before I try using it. (I'd connect the speakers to the switched connection, turn the switch off first, then after warming up switch the speakers on.) However, this approach probably isn't advisable--I've heard safety rules say that one shouldn't use electronics that are acting up.
As for repairs, I'm not surprised that Linn isn't interested--they seem to have no interest in supporting any older product. At one time, I was a Linn supporter. I am not any longer in large part because of the lack of support on older equipment.
You might be able to find someone who could fix it.
Whether or not its worth fixing is another question. I don't think the Intek was the best amp ever made, but if the repairs are cheap enough it might be cost effective vs. buying a new entry level amp.