I was able to fix the locomotive. I think it was my own fault it wasnt working - some of the sound and effects were aliased to the Black 5 (as per you) and the Challenger add-on (per me). I did not enable the IHH addons in the scenario, so I think thats why they werent showing up.
I also fixed the coupler issue by aliasing to the default coupler (had to move them slightly to be in correct alignment).
I also added a headlight.
Its working great now!
One question I do have; with 60 loaded coal cars, I'm getting a wheelslip notification with the train stopped and 0 regulator. I also get it intermittently from about 20mph and faster regardless of the regulator setting. I noticed when this happens, the forward pilot wheels and aft wheels spin rapidly, but the driving wheels do not. Does adhesion/TE need to be raised or is something else going on?
