I have no opinion. All solutions sound viable - just depends how much work you want to do yourself.
I would definitely take the cable off (John B suggests there are connectors both ends) and see which wire has the break. As a quick-and-dirty solution, solder a new wire in parallel with the bad one! Or you may find it is just a bad solder joint that can be fixed.
“Use as an excuse to convert to R/C control and battery power”.
DIng ding ding. I think we have a winner! 
John (@John_Bouck ), thanks, I had no idea what this cable was called. I’ll hunt around to see if I can source it locally.
Pete (@PeterT ), I inspected all the solder joints. They looked good. I also tried to apply power to the motor by jumping past the cable, so I am pretty sure that is the culprit.
Still mulling R/C…
Eric
I’m all for supporting local business when you can. If a local RC Car/Plane hobby shop doesn’t have them, there are lots of choices on Amazon. The problem with Amazon is you probably need to buy 10 or more. At least the 10 on Amazon are usually less than a two pack at a hobby store. That’s assuming Amazon serves the islands.
If you go with the 3-wire servo cables, you can buy header pins that are spaced the same to make a male end connector. Headers usually come in 15 or more pins, but are easily cut.
The Servo comes in various lengths. I glue the female end solidly on the floor of the loco. And the male hanging out of the tender. I glue it so that the exposed points in the male face down when it is plugged in. This is so you know the orientation of the plug. It does have a tiny key slot for this very purpose, but visually is easier. I also have put a white dot on the male meaning “this side up”.
I use these on all my battery cars and have had no problems. People say the wire is too thin for high amps, but I have not had any heating or problems.
Got mine on Amazon.
These folks have never looked at the wire size used inside the locos. It’s usually pretty light!
Jon,
I used to use the JST between 4 Aristocraft PA’s for MUing. Pulling 100+ freight cars.
Never had a problem. I used them on all my conversions.
Then a friend who runs Large scale DCC (Zimo) was using the servo type. They are smaller and the wires look better between the locos. I asked about problems, and he said none.
I now use the Servo’s exclusively.
The JST wire is regular wire, which can be stiff.
Servo’s use silicone coated wire, with finer copper strands. It’s very flexible.
JST cables are flowing…CINCHOUSE made an AMAZON order, and I piggybacked off of that.
Eric
Cool. But you didn’t say what CH will use her JST’s for…?
Oh, she’ll probably just give them to me or something… 
Cables are on hand…Waiting for a good opportunity to install them!
I carry the replacement LGB type plugs and sockets, if you need any. Go to my Website’s Plugs & Cables page. LGB Trains | Old Dominion Railways | Repairs & DCC Installs | United States
Thanks! I appreciate the information.
Update…
Being at “all stop” for want of the correct idler gears to repair Gustav, our LGB m2071D ( LGB 0-6-2T: BadMotor, Bad Gears, Both, or Something Else?) , I turned two on this, the next item on the Triple O - 2023 Plans & Objectives list, but only after I did some M.O.W. work to get trains rolling. I find I work better with the rolling motivation in the background!
Once that was done, I reread this thread. I also did one last cost-benefit analysis of adding a battery and, possibly, an R/C system. I decided to just fix the cable as I would need that for a battery conversion, anyway, and a battery system beyond a DPDT switch would destroy my budget for the next 6 months. Maybe I can get some Lithium Ion batteries my next run to CONUS, as the shipping is outrageous.
O.S. was working on his plane, so I had his company. Other than that, it was just the 1:24 gang, the tech manual, and I. I retested everything to make sure I understood the problem then proceeded to break down Nuernberg.
There are some tricky screws, but nothing like North Star, our venerable B’mann 4-6-0!
I checked one more time for broken soldering points…
I fixed that and decided to give the motor box a thorgough cleaning. There was some “gear-fetti.” I used Q-tips and alcohol to remove the old grease before adding a smidge of fresh gear grease. I also took the opportunity to oil the running gear. While beginning reassembly, I noted that one of the bus bars had come out of alignment. Closer inspection indicated both may have been kapakahi for some time. I also noticed the springs in the pick-up shoes had long ago lost their springiness! New shoes are now on my parts list. After getting everything back in place…
…reassembly was pretty easy (I did drop one screw…a small one…naturally). I tested as I went to make sure that I had not knocked anything out of place. My test track decided to give me grief, so the 1:24 gang and I took Nuernberg out to the tracks, and gave him a run…
Video: Nuernberg on the Blocks
It has since dawned on me that this tested nothing since, of course, the drivers picked up electricity from the tracks via the test rollers. Not to worry! Remember those unspringy-springs? Because of this, the pickup shoe dipped under the flange of the closure rail on a switch that is partially disconnected from the ties. I assure you, all now derailed drivers turned mightily with only the cable from the tender providing power!
I jammed a bit of HardieBacker under the switch mechanism, and all was well. It was nice to see how slowly and smoothly “he” could pull with all wheels sending power to the motor. To be honest, this is the best Nuernberg has run in years. All that was left to do was to let the crew high-ball
back to the shops and Pu’u’oma’o…
Video: 1:24 Crew Heading Home
…and celebrate my success!
Thanks for all the tips! On to the next project!
Eric
Huzzah!!!..!!!
I rebuilt two LGB Moguls to install Rail Pro with battery power and I used plugs from a kit I purchased on ebay, wiring connectors kits for 18-26 gauge wire for sale | eBay
Since I wanted plugs that were a minimum of 8 wire connections (engine to tender) I just purchased a kit with several numbers of wire connections, as I would have other uses for the other plugs. These plugs are for 16-26 gauge wire which will cover all the size wires needed for Rail Pro operation and for most engines electronics used today. I also purchased wire (stranded not solid wire) on ebay in 5ft. lengths and in several colors so each light, etc. has it’s own color code. I believe I purchased 22 gauge wire for all functions with the exception of 18 gauge for the power leads for the motor. Just remember to get the kit with the small/miniature plugs, as many kits have plugs that are too large for what you want to use for your engine.
trainman
Thanks for the tip, John!
Eric, here are a few pics of the wiring plugs that I made up from a kit. The wiring plug, new drawbar as I did away with the LGB hook coupler as there wasn’t enough room for it and the walk plate between the engine and tender. These were just a few of the updates to the two LGB Moguls that I rebuilt and added Rail Pro.
trainman
Thanks, Trainman! This is definitely the direction I want to take with this mugul, though I am probably going to leave it in its stock livery.
ERic
Should work out just fine doing it that way. I just like to re-due all my engines and rolling stock, it the part of the hobby I like best, being a modeler first and a runner second.
trainman
