Soar Valley Light wrote: โSat May 09, 2020 7:52 pm
I feel a rewire might be the order of the day, my only worry is that there might be something in the receiver that's causing some or all of the trouble. Changing that as well takes well out of my comfort zone!
We all need to push the boundaries of our comfort zone now and again.

Just ask for help with anything you are uncertain about and you'll get there.......
Once you've got the new wiring loom, test the various parts on the bench with ordinary dry cells, before installing things in the loco. These cells have a high internal resistance and can't deliver enough current to get things hot in a hurry.
Don't use alkaline cells, they can deliver a lot more current than the ordinary type and definitely don't test with rechargeable cells until you know everything is working. Some r/c electronics can get funny about running on 6V, so use three dry cells, not four.
Chris's advice to splice on new leads is a good one, but make sure you use shrink tube to insulate the joints, not tape. Tape won't last long in the heat of a live steamer and you'll be back where you started.
So, connect up the receiver first to find out if the magic smoke is still inside. If that looks OK, try a spare servo in each of the outputs. I'd try a known good servo first, before you try a repaired one, so you aren't chasing two possibly faulty devices at once.
If that all works on the bench, you can then start installing it back in the loco.
If you get the right wiring loom it should be 'plug and play'. Just take notes and photos as you remove parts from the loco so you have a reference for when the time comes to replace them. Your other steamer should also be a useful reference as you go.
Regards,
Graeme