A couple months ago I bought an MTH Premier Proto-Sound 3 SD50 (20-20424-1) from the local hobby shop. I noticed when I removed the locomotive from the box that the grille over the smoke stack looked a little warped. I thought nothing of it even though my other SD50 (20-20424-1) which I bought a month later looked OK.
Well, this is what the grille looks like now after 2 months of running...
I've already contacted MTH Customer Service about this and Midge is taking care of it. However, I've noticed that the same thing is starting to occur with my other SD50. None of my other MTH engines that I had/have experienced this issue. I'm thinking it's just flimsy plastic for this model.
Once I get the replacement part I'll probably just operate the locomotive without the smoke unit turned on as I figure the replacement grille will eventually suffer the same fate.