One of my locomotives, a old Aristo Craft RS3 diesel developed a weird issue today. It kept slowing down to a near stop in a couple of spots. First I thought it was track conductivity issues, cleaned the hell out of the rails, even took the track clamps apart for cleaning, even cleaned the loco's wheels. After no improvement I tried another loco, a last generation Ariso Craft FA1 cab diesel and it ran around fine without stalling. Gotta open up the RS3 and see if I can find the problem, I suspect a splt drive gear spinning on its axle. Sadly Aristo is out of business so getting parts is tricky. Bachmann makes repro complete motor blocks but hopefully its not that bad.