There are lots of replacement xfer switches on the market, for 30 and 50 amp RV services. My 2013 ACE was equipped with a 30 amp service and a Progressive Dynamics PD5100 xfer switch I think (made in US). It is still working fine. We are not full timers, but I run the gen every month (except during the Winter) so the xfer switch does get some action.
I would suggest looking at what you currently have (maker and part number) and see if it is still available on line. The reason I suggest that approach first is that a direct replacement should be a drop in install......no rewire, cable length changes or space issues that might occur with a different maker etc. Of course that assumes the original part number still has the same dimensional replacement available with the same knockout locations. Might be a risk after 12 years. On line shopping lets you compare specs, dimensions and costs if you want to see what’s out there.