I don't recall any particular problems with the diaphrams, but it's been a while since I've seen them, so it's difficult to recall too much of anything about those cars. It sounds like flash would be the most likely cause of your problem. I didn't disassemble the interior: the sides disassembled themselves from the car

, but were easily snapped back into place. Some of the underbody detail fell off, too, but that was ca'd back in place, although the manufacturer's use of engineering plastic for these detail parts is, in my opinion, not the proper use of this material. The step-trap covers in the vestibule are also made of this material, and I had some difficulty getting them attached, as the fit was not the best.
While I'm at it, am I the only one dismayed by the persistent misuse of engineering plastics, such as Delrin, Celcon, etc., by manufacturers? While I can appreciate the rolling qualities imparted by Delrin trucks, they don't hold weathering paint all that well. And handrails on diesels? I know that there is paint that will adhere to this stuff, but really!

We also get detail parts moulded in this material (Proto is a big culprit here), giving us grabirons more than a scale 2" in diameter, and various other parts that don't match the colour of the model that they're applied to (make sure to buy some more of that special paint), not to mention that if the mounting holes are sloppy, require a special glue (cyano-epoxy) to secure them. We modellers are partially to blame for this situation, as we clamoured for more detail, with no more cast-on grabirons etc., but the manufacturers dropped the ball on this one: I have been impressed to tears with the skill of the diemakers responsible for these "gems", but one of the keys to doing a task well is choosing the proper materials. Now, back to our regularily scheduled programming.

:-D:-D
Wayne