They will overhaul a TM but it ain’t cheap. Any structural damage to a shell, they will recommend a new shell and it ain’t cheap. They can do the bag seals but it ain’t cheap.
I had them replace both the shells (only A/C & awning were reused), lift arms, torsion bars, and bumper plus a bunch of odds & ends on my 2007 3326 due to saggy roofs. It cost almost half the price of a new TM. But we really liked the 3326 and it isn’t made anymore. It wasn’t much more than going and finding another 10-15 year old used 3326 in supposed good shape. So we went this route and now we have a 3326 that is brand new in all the TM-specific areas that should last us another 10-15 years easy, and it’s new so I will know exactly what has or hasn’t been done as far as maintenance etc. But it sure as heck wasn’t cheap.
I’m currently refurbishing an old 2720 and have contacted the factory for help replacing all the bag seals and velcro flaps. I know it would be done right but it ain’t cheap. I could do it but I need a second set of hands and can’t seem to find anyone interested in making a some dollars for a weekend of work, including my two out-of-work brothers. I’ve even offered to have a bag seal party with a few folks who needed bag seals replaced; be my second set of hands and we will get both trailers done. No dice. End rant.
Point being unless it’s an oddball model or some other extenuating circumstances, factory overhaul usually isn’t cost effective. But it has been done. Here’s a video of them replacing a front shell due to (I think) a deer strike.
https://youtu.be/jTdnUdWnFh4