My BR260 started to do something really strange. It was loosing power progressively. Each day it was able to pull from less wagons. Finally at full throttle started to move slowly and after few centimeters stopped.
The design of this machine is a mess inside. The power is taken from the wheels with a soldered wire for the positive and with a screw that attach the little circuit to the chassis. And power to the motor is given by a soldered wire for negative, and through a week contact for the positive.
I can't figure out why it needs resistances, reel and other electronic stuff to run a small train... I tested the motor and it runs perfect, I also installed again the dummy and the wrong behavior was also reproduced in DC.
Finally, I removed everything and install a simple NEM connector and a Decoder. Now the nurse discharged the patient.