Hi
I recently converted the BR111 from the 2867 set to mfx using the Marklin conversion kits/sound decoder (60941/60977). I also replaced the slider as the old one was worn

The locomotive runs quite well, but has a tendency to hesitate/stall on straight sections after exiting a curve. The problem is most pronounced when the locomotive runs clockwise, and particularly when it is running in reverse (slider to the rear). If I jiggle the locomotive, then it will start moving again if it has stalled completely.

I've checked the wheel spacing (OK) and there is no sign of hesitation if I apply power to the wheels directly. The slider appears to be straight and level. The track sections are clean, and in fact the locomotive often hesitates over the power connection segment as it is located directly after a curve section.

Can anyone suggest a cause for this behaviour and any possible solutions?

Thanks
Les

Hi Les
Once the slider is new and the track is clean INCLUDING the studs prone to oxydation, you must check:

- wheel cleanliness ( Isopropyl Alcohol+ cotton bud)
- axle clealiness by lubricating, then letting the loco run upside down, then cleaning the residue (oil with contaminent)
- possibly adding another ground return on each bogies using thin, flexible wire as included in Märklin decoders. The more sophisticated MFX does not like tiny power and signal interruption. When the loco stutters it is because the processor in the decoder is rebooting. Most manufacturers compensate this increased sensitivity to contact issues by adding power packs

I hope this helps
Jean

NOTE on many older locos (the 2867 train is a MHI released in 1991), especially with diesels and electrics, the ground return was only made by two prongs on the slider bogie (only ONE bogie and no wiring) Today, this is not enough anymore

I would recommend additional earthing too. Add one to the motor bogie under the crew that holds on the brush holder.