[Arran]

I think that I would try to put it back to the way it's shown on the schematic, someone's been playing around inside this set, possibly a Ham who thought his license was an engineer's certificate. That bolt with the wire wrapped around was bad enough, now it looks like they replaced a six pin plug and socket with five pin ones on the power supply. There is almost no point in trying to trace this out, it's like any other hacked up wiring job, there is no guarantee that the last guy who had his soldering iron in there knew what he was doing, or that it even worked afterward.
Regards
Arran