Well, I started this thread, so I will comment! I sent the loco back to Bachmann, and just got it back today. Mine is the 40505 Berkshire. Report says they lubed the chassis, repaired loose screws and connections on control board and loose screws on motor. Put it on the layout about 20 minutes ago pulling a light load, about 8 PW cars on a level loop. So far, so good.
1. This unit has a ratio of not even 12:1. maybe 10.5 :1 or so between the motor and drivers.
2. The extreme motor heating I was experiencing was not a load issue, part of my original troubleshooting was to run just the loco and tender, and even that caused it to jam, stall and get scorchingly hot.
3. It seems to me that, since it has been returned, the driver axles have much less axial play; the whole driver wheel assembly seems much tighter. It also appears that either the leading or trailing truck or pickup rollers may have been replaced, I see that the drivers are very well oiled, but the first time I ran it I heard the squeal of un-lubed Williams trucks and rollers. Haven't oiled anything yet, want to see how long it will run. Before the return to the shop it would run not more than 5 minutes before it got hot and virtually stopped, if it didn't jam first.
I am not sure exactly what they what they did with this loco, but I am not going to argue with success.