I have to ask, when did you last oil it? The brushes look to be ok so that would be my immediate thought re the Loco itself.

But... it could also be the controller. It's possible the wiper has worked loose and is only making contact internally at the higher ranges.

A quick check you could do for that would be a lamp on the controller output but no loco on the track. The lamp should glow even at a very low setting and get brighter as you increase it.

If the lamp does not come on at all until you have the knob set high then that's likely the issue.

However if the lamp glows across the full range, I'd be suspecting the Loco

Hope this helps

Cookee

Yes, those items, plus clean the armature and copper commutator brush plate. Some older Locs., like my br 89 hardly move until the speed dial is above at least 50 or 60. The old field coils, 3 pole vs. 5 pole permanent field magnet motors.

Thank you all for the feedback and suggestions.... greatly appreciated!

I oiled the wheels and gears etc per the Marklin instructions, and replaced the motor brushes.. this provided minimal improvement (but still glad I did it, I really learned to appreciate the engineering, after taking it apart).


I then did a pretty thorough track cleaning (first with a clean paint brush, then a yellow rubber track cleaner), including the middle track studs. This helped pretty significantly.. I can now get the loco to go around the track several times again, without stopping, which is great.

However, if I turn the transformer past 150, the loco will immediately stall. I'm considering taking the transformer apart to try to inspect/repair in myself....