Thanks for the reply, Tony.

Your description is totally correct. It's been driving me nuts, and I'm still no nearer to finding the cause.

I knew that my DC jack was a bit flaky, so for a long time, I figured that this was the cause. When I replaced it, I figured the problem would go away, but it didn't.

The only other information I should add, is that I have removed some of the wires from the sled connector. These are the tuner connections (as I never use it), and the serial port. I did this to reduce the wire count when installing in very tight surroundings. At the same time, I also resoldered all the other connections.

I might try making up a diode lead, and see if that helps. I'm not seeing any of the other symptoms, but you never know.

Andy.