@Knight007 posted:, I opened the tender and indeed the tether is completely hardwired to the boards, there is no simple plug at the other end. After fiddling with the tether and plug that connections to the engine while it was running, I found that there may be a wonky wire within the tether cable. I rotated it a bit at the cusp of the tender and "locked it down" and it seemed to remedy the surging, but it's obviously not a completely permanent fix as there appears to be a wire breaking inside the bundle in the cord. Not sure what to do now as I don't have the soldering skills to replace all those board connections with a new tether. Perhaps I'll just have to be careful with the position of the tether as it goes between the tender and engine and adjust it again if it starts acting up.
Might work for awhile ????? Hopefully a second wire's insulation doesn't rub off against the first wire and turn the board into an expensive piece of toast. 
Sir Knight , do you have a good model train repair shop nearby or a favorite brother -law who repairs electronic equipment ? Of course there are competent people on the forum that might be able to get this new tether attached to the wires at the board for you at a reasonable fee . 
