Looking at the exploded drawing of the N scale challenger, it looked like the headlight housing should just lift off... and I was hoping that I would be able to pull the light out (don't know if it is incandescent or LED) and replace it with a small warm white SMD LED. If you figure it out, please share what you find...
Dave,
Thanks for info. You are correct, my 2007 loco diagram also shows headlight housing as a separate part (maybe glued in) enclosing the vertical incandescent lamp. Per SpookShow, the 2013 run is when they switched to LED's. I'll keep you posted on my progress (if any).
Conrad