Quick Ques Re: motor/brush test.

[Gerome]

Is it dangerous to a decoder to test the motor with direct DC leads to the bushes/pickup while the decoder is still attached? 

I imagine one should not touch DC to the decoder rail pickups, but will current flow back to into the decoder from the grey and orange motor leads?

[jeffrey-wimberly]

In a word, no. I use a Kadee Speedi-Driver wheel cleaner on a DC pack to clean my loco wheels and have never once had any decoder issues because of it. After some experimentation I can say this. DO NOT connect DC power directly to the motor while the decoder is connected. It will smoke the decoder. It sure did it with this El-Cheap-0 Bachmann Bach-1 decoder.

[Vail and Southwestern RR]

I may have gotten myself confused, but I would think the wheel cleaner is appying the power to the wheels, not the motor directly.

I would not put DC onto the motor while the decoder is attached.  That's pretty much the same thing as having the brushes shorted to the frame, which is know to have the potential to let the magic smoke out.