Vinyl insert is coming off? The corners or where it goes over something was the weak point on ours. After glue and new insert, OK for couple years, then same old problem. After seeing what others did, I put little screws thru vinyl insert into its frame (to hold better). Not entirely happy, but problem solved. On straight runs no problems it stays in place, corners is where I had my problems. They come in different length rolls.
http://www.campingworld.com/search/index.cfm?Ntt=vinyl+insert&N=0&Ntx=mode+matchallpartial&Ntk=primary&Nty=1&Ntpc=1&Ns=p_sort_default And I think somewhere I saw some with the words "heavy duty", but my size so didn't check out further. Hope this helps.