I had to unsolder the stock coated wires and add my own between my 2006 release J tender and engine because of the coating coming of and causing intermittent shorting.
I ran great except I burnted out the head light checking the connections on the engine board( LEDs do not like track voltage) to find which one were motor leads. Then 6 month ago it quit so I just remove the tender board and solder wire to the tender leads work great again UNTIL I put the boiler shell back on. Yep metal boiler was shorting the frame haves up front by the stack
so I painted it and will add more tape.
I know the stock wires had problem with the varnish flaking off you can solder wires between the stock connection ( I only used two wire no room or patience for more )