I wanted to write this up as a separate topic in case anyone else runs into a similar issue with their Williams engines. If you have a Williams engine that stalls frequently, check the third rail rollers!
I picked up this Williams FM Trainmaster at York as a donor chassis for a future 3D printed project. The locomotive was very inexpensive and appeared to have an Electric Railroad TMCC upgrade. This turned out to be a great score-- a DC Commander with a full Railsounds package and a pair of Electrocouplers! Of course, there was a reason for the great price. The engine was a basket case, it wouldn't always start and when it did, it couldn't run more than a couple inches without halting and powering down.
After I got home, I completely dismantled the locomotive and went through the usual problem areas. The TMCC installation looked OK and I verified the wiring against the ERR diagrams. There were no broken or pinched wires, continuity was OK, even the wheels were relatively clean. I even cleaned out the gearboxes and applied some fresh grease to make sure the motors weren't getting bound up. Nothing seemed to make a difference; the locomotive would start up with sounds and command, but it would sputter and die as soon as it started moving. Disappointed, I pushed the locomotive to the side and let it sit on the workbench while I contemplated its strange symptoms.
This afternoon I decided to work on the engine again. I clamped jumper leads directly to the locomotive's frame and pickup arms and was surprised to find that the locomotive ran perfectly well in command while upside down in an engine cradle. This convinced me that the ERR boards were fine, they just weren't getting power somehow. After taking the trucks apart again, I found the cause... there was rust INSIDE OF THE PICKUP ROLLERS! Here's the photo I took to prove it-- you can see the gross brown rust on the long pin that holds the roller.
I guess the engine must have sat around in a humid environment for a while. Rust is a horrible conductor so it makes sense that the engine was shutting on and off as the rollers turned. After a copious amount of WD40 and a bit of work with the Dremel tool and some Q-Tips, I cleaned the pickups inside and out, bolted everything back on and put the chassis onto my command control layout.
Runs and sounds great now that it's getting some power!
Anybody else seen this issue before?
edit to add clarity