Zerosquare

I do. Dusty fans, VJ hogging the CPU, thermal shutdown

The Pro-Controller also has better buttons. I don't know how it's done internally (I don't own one, I just tried a friend's), but the tactile response is definitely better ; the buttons feel responsive, unlike the somewhat "spongy" touch of the standard pads.

Were are you located? There's a possibility that the Jaguar you have is from a different region and uses a different video standard, which would explain the B&W picture (though it would be a bit strange for a foreign console to end up at a garage sale, but who knows...)

In theory a damaged part inside could cause this problem, but it's pretty unlikely to happen.

I would recommend using at least a composite video cable anyways if you want to enjoy your Jaguar. The RF output is pretty bad and the sound is mono only, which is a shame for playing Tempest 2000

If your TV has a SCART socket, get the SCART RGB cable, it gives the clearest picture. Otherwise use the S-Video cable ; only use the composite cable if your TV doesn't have a S-Video input. Unfortunately those cables can be pretty expensive (for what they are) to buy, but you can build them yourself if you can handle a soldering iron.

Nice !

Looks like your Jaguar has more serious problems then. Unfortunately it's a complicated machine with potentially lots of things that could cause a black screen. Finding the problem without at least an oscilloscope would be pretty difficult.