Hi Ken, Chris and John,
Thanks for all your thoughts so far.
Ken - I tried that adapter from Jaycar as you suggested, but no joy.
Chris - I'll give your idea (a replacement CAT5 cable, and jiggling that inside the mount) a go.
John - I was able to open the mount up yesterday and found it difficult to actually see the board that has the plug and switch on it (as the wiring are too short). I didn't feel too keen about disconnecting them from the main board as I didn't know if I would be able to get them back in there, but I used the multimeter (connected into the power plug itself and onto the soldering on the main board (at the terminal where the power plug plugs into the main board, and measured complete resistance, so it seems like the issue is between the plug and that main board, somewhere. Do you know how difficult it is to reconnect the wiring once I get them disconnected? Can you recommend any way of doing so (rather than just yanking on those delicate wires)?
(To clarify, when I talk about the main board, I mean the one that doesn't have the plugs and switches attached to it).
Thanks again for your thoughts,
David