Were you effected by the wide spread (zinc rot?) self destructing Weaver troop cars some years ago?
This didn't effect the total production of troop cars. I was lucky, only 1 of 4 of my cars had the undercarriage expand causing it to crack in half. In a testament to the strength of the shells on these cars, the center of this undercarriage had a downward bow of an inch away from the bottom of the body shell. The side door glue seams broke free, possibly allowing enough flex relief to not crack the shell. At the time I remember a guy being sickened by the fact he owned 50 or so of these cars. I don't know if this was zinc rot, as the cast undercarriages actually swelled lengthwise. I was so disheartened I just loosened the undercarriage screws and put the cars in storage. Well, I just dug them out, and am happy to report the other 3 didn't follow suit. Weaver did offer a fractional discount that could be applied towards another item, but as I recall it wasn't near the troop car purchase price, and you had to pay the shipping back to Weaver.
At this point in time, do you think we are beyond the danger of these undercarriages expanding?
I might try making a wood undercarriage and affix the detail parts, I can't think of any other repair solution.