Yes, the error does say max-coal-mass. Actually, the original loco that I downloaded from a third party source came with a missing Interior asset and would not show up at all. I tried to substitute one of the default Auran steam interiors, I think it was the Big Boy, and the loco appeared in the Depot and could be placed with Surveyor, but when the scene was run, this error appeared appeared. I downloaded the loco again from DSL and the missing Interior asset was installed, but I still got the same error. Thanks for putting me on the right 'track' about this. I'll check out the threads and other information you provided.