None of my 10 other Märklin models has ever acted up this way before (and some are as old as 50 years).

I am perplexed that my latest purchase in the M# 29487 Zürich S-Bahn Startpack turned sour so fast! The German Online dealer agreed to make the exchange when I had a chance to visit there personally before Xmas.

But surprise! He had to open two new box sets before we found a model 37347 that worked -- and now it too, after my return to Canada, and only about three hours operation has the same gear train blocking problem.
?

Help!

PS Is there a CV parameter change that cures this? I doubt this as the moter just doesn#t have the necessary startup torque to overcome
the blockage.
PPS Short of removing the drive train and taking off one of the two axle driver gears, is there a less drastic solution?

THX for the reply Dale.
I made sure that the gears were clean and not excessively lubed.

I had the same problem, with the same kind of loco! Not from the same SET as you, but the same loco from another starter set (An older swiss mega starter set, I suppose)

It seemed like metal-debris binding up the gears. But I didnt seem to be able to clean it well enough. In the end I solved the problem by brute force; Forcing it to run for some time at max voltage (Once it got going, the inertia would keep it running). Mechanically it now run excellently.

I went back and looked for my notes I made when I had a similar problem (unrelated to the bit of dirt issue)

Here it is: https://cabin-layout.mix...09/rough-gear-train.html

I concluded it had something to do with the lateral play in the axles.