My 3696 I got used some years ago, was seized when I got it but I remember using a small screw driver to free up the motor. That wasn't so hard and after adding a few drops of oil it ran well. I got it out again last week and I noticed it went slower forwards than back wards, but on occasions it would go faster in the forward direction. The motor is still free. Although it is "digital'' it really is like a delta with the uncoupling ability.

Does anyone have any ideas??

Dereck

Hi Dereck

I suggest you open the loco, clean its gears if needed remove the brushes and gently rotate the wheels to check for seizing or hard points in the gears.
I use a toothbrush to start cleaning the gears for possible "things" stuck between 2 teeth.
The motor should rotate without any friction (almost!!)
If it was a while before it last was used you need to let it run a little while and its running will improve rapidly.
My nightmare: when a tiny bit of ballast get stuck and is difficult to locate where it is.
PS on second read of you post the culprit may be the brushes which need change and springs need checking (runs slow and then run fast)
Bonne chance

Jean

Thanks guys. Last night I removed and inspected the brushes and commutator. Brushes are virtually new, and the commutator surface is nice and shiny. By moving the rear wheels in either direction, the motor turned freely. I also could not see any obstructions in the gears.
BTW, this is one of those locos where the motor drives only the rear wheels. The coupling rods do the rest. I placed it on the track and it started off, then on full throttle [on the MS2 ] it went slower that in would in reverse. It went over a 5117 point then accelerated so fast it rolled off the track!!!!!!!. From then on it seemed to go as fast on forward as in reverse but when the throttle is brought back we are still getting the slowing down and speeding up syndrome. Oh well, its an old loco, and sometimes some of my early 50's stuff does the same. It doesn't smell or sound any different from normal.,Its relatively quiet say compared to my 34121 P2 which just about screams if and when you give it full tit..
Dereck