Ken,

All Mantua cabs, diecast or plastic, were separate pieces.

The diecast cabs were held in place by a screw through a smallish projection (tab) at the front top of the cab casting. The tab would be the first thing to break off  if the was any sign of “zinc rot.”

On mine, the tab was/is on the top rear of the boiler casting.  A screw would go up through the cast metal tab into the underside of the plastic cab to hold it in place.

Don’t bother to ask how I know this. However I’ll tell you my first HO locomotive was a 2-8-2 I received for Christmas 1949. One day my perfect appearing boiler, cab and tab were all separate pieces.

So, that happened to you, too!  I just took a little longer with my parts.  At least, the side and connecting rods were not zamac castings.  I wonder for how long the chassis castings will hold up.

Wayne Long