Do yo ever have days when everything you touch on the layout goes wrong? I am having one today.. Sorted quite a few issues out but now I have a problem with my RE620 Xrail
Lights, functions etc are working but travel in either direction judders and stops after a short distance. Any guesses? Oil, grease, slider, motor brushes, a loose wire or something expensive. Visual seem OK but I know if I explore further randomly I will mess the whole thing up!

I have the same problem with my 37306, Zugkraft Aargau Re 4/4. I just sent it to Rick Sinclair for repair. It started to exhibit the behavior after maybe a 1/2 hour of run time.

Regards
Roger

So I seem to be having a better day today than yesterday.

I took the body off this lok for the first time since new (2years?) - wow its all very neat in there. A tiny drop of oil in the spots set out in the book, my old tooth brush was used with a small amount of contact cleaner to remove residue from the wheels and slider and the slider firmly positioned in place. And tried a run again first time out it did stall but then I ran it at very lower speed 20/140 for quite a few circuits - no problem up to 40/140 no problem up to 60/140 no problem - left it there for the moment then added it normal consist of long freight wagon 10 or so (about the limit for my layout) no problem! I don't tend to run this at high speed it looks far more dignified purring round the bends!

Have just tried again now this evening and it seems to be fine.

I hope this is the solution. I don't mind a little routine maintenance - and perhaps I have shown that I do not do enough. I admire many of the forum member who fill me with wonderment at the projects they take on particularly converting older loks but that is not me`. I am a fudgy fingered grumpy old sod who likes to spend hours on Scarm redesigning his layout and even more hours simply watching the trains go by and shunting till the cows come home.