I recently did an install on one of the more recent releases of an Atlas GP38-2 using the TCS M1 decoder. While this install is similar to other installs I have presented using a wired decoder instead of a board decoder I discovered some differences that made it worth it's own post.
After dis-assembling the mechanism I discovered that the motor had a different type of brush holder than those found in most Atlas models. This model uses the Kato style of brush holder with a separate cap.
The plastic motor saddle had also changed. Because the brush holder with cap sits flatter than the one piece type, the saddle had a block on both top and bottom. I found it necessary to remove the top block with a file to get a good fit.
The board requires the same type of preparation as the board did on the Atlas Master Line GP7 that I did about a year ago.
For more for details on how prepare and wire the decoder to the board check HERE.
This model comes with the little spring clips on the original LED board. I've never had much luck with these and the ones on the board fell off so I used the solder method to thicken the board for a good fit into the frame.
After re-assembly the mechanism looks like this photo. The model I did was actually a GP38-2 but a master line GP38 should be an identical mechanism. I test ran this model with an earlier release GP38 and the speed of this new motor seem to match the older release perfectly.