Thank you for the advice to reach out to Micro-Trains. They put replacement trucks right in the mail quickly for me. In the meantime, I did try...
I'm pretty confident that it's the two wheel sets. When I move them with my fingers, I can feel where each on hits a "bump".
Thank you. I'll run it for a bit and see if it shakes out. If not, I'll reach out to them.
I just purchased a boxcar from Micro-trains' latest line. Specifically 074 00 190, a 40' ATSF plug door. The wheels on both trucks that are...