I understand this should not be happening but maybe a solution would be 3D printing?
I am don’t know the alot about 3D printing but would 3D printed side frames work as replacements with maybe brackets on the side frames to attach where needed?
I had one example so far a K line Ewing Oil tanker whose trucks crumbled on original unpacking. I fear more rot to come as more units are unearthed from the Underalls.