The good news is yes they can be restrung. In fact if you go to the Winnebago web site in tech info ( I think) there are actually diagrams and instructions on how to do it yourself. If you can't find it just call the main phone at Winnebago and they will tell you where it is.
The bad news is it looks pretty complicated and even though I consider myself pretty handy I chose not to subject myself to the aggravation.
We were in Port Charlotte FL when we needed to get two of ours redone. There were two RV repair shops in the area that had outside people that could do the job. I think they only charged around 35 bucks each and did it in less than a week. I had the shop install them in the coach too for a few extra bucks.
I'd call RV repair shops in your area and there may well be someone that does these things there too.
Good luck, Steve