On a trailer that has seen over sixty years on this planet and is as collectible as yours, I would
certainly be concerned by cracks on the frame.
Has your warrantee expired?
Seriously, I think a qualified RV tech that has a reputation for doing good welding would be a goo place to start.
ps: how about a bunch of nice photos? you are obviously good at taking them...
__________________
“Courage is being scared to death, but saddling up anyway.”
...John Wayne...........................