Dealer Parts Department or Salvage yard
I think you will need to be heading over to the nearest Thor dealer. Hopefully their parts department can hook you up.
Or Google used RV parts there are several outfits that salvage RV parts that maybe able to help.
We are lucky we live in NW Indiana about a hour and a half from where they build them in Amish country. Elkhart Indiana has at least half a dozen RV salvage yards. Good luck in your search
2018 ACE 27.2
Toad 2019 Jeep Cherokee Trailhawk
Roadmaster Falcon All Terrain Towbar