I also used the plastic cover from a box of Christmas cards to keep the contacts from touching. I used the part that is at a 90 deg angle and cut to fit and slid the plastic into the split part of the chassis. I have had no problems so far.

Thanks for the reply. It's a much simpler way to do it and I'll follow your advice.

I want to install a soundtraxx sound decoder into a N scale GP-7. Please help me to understand how to connect track power to the decoder. The factory decoder has spring tabs that contact the frame. The trucks also have spring tabs that contact the frame. When I remove the factory decoder pc board, I need some other way to connect the decoder to track power. What do you suggest? I planned to drill and tap 00-90 holes in one end of the frame and attach the red and black wires from the decoder to the frame with screws. Should this work? I am having problems drilling into the frame. What is the frame material made of?