SZ, thank you for your time and here are the answers:
1. Do you know what the amp draw on the loco was ? If it was on a club layout, do you know your loco was the only thing being powered ?
It was the only engine being powered, smoke was off, current draw was 250 milliamps with no train, only slightly higher pulling 6 plastic cars.
2. Did you receive the instruction book with the loco ? It will be of no help in troubleshooting per se, but does tell you where things are [ more or less ]; for example, have you looked inside the gear box to see if the grease has hardened , etc ?
I did not receive it but I downloaded a copy. I haven't looked inside the gear box yet.
3. Do you know if the problem is electrical or mechanical at this time ? You can remove the loco body and turn the motor by hand, for example.
I don't. it runs smoothly, just slowly.
4. I would turn the smoke unit and sound off to reduce A draw, etc; I image those controls are on the bottom of the tender ?
Good idea, I had turned those off before I started.
5. Do you have test stand rollers or the ability to 'block up' the drivers and run it from clip leads ?
I do and that will be the next step. The sound works, but it isn't that great. I will likely remove most of the electronics.
6. Do you have any other MTH locos and are thus familiar with their non-NMRA volt vs speed curves ?
I have 3 of their diesel engines no other steam engines. I had some of their 3 rail engines previously.
Good luck. With MTH on DC you'll need it.
Thanks, sounds like I'll need it.
Best regards,
SZ [ who is a DC 2 rail person with some MTH locos, but none steam ]