I have a Spectrum desiel loco that is DCC on board. When it is parked on a side track for no reason it will take off on its own. You never know when. It only happens when other loco's are running. I had to isolate the side track with a insulated rail jointer and a seperate switch to keep this loco in its place. I tried to re-program but it still takes off on its own. It responds to its address and runs fine when called upon. Is the decoder bad. It only has about 30 min. run time.