Who makes the enclosure?
If it's Shower Enclosures of America aka SEA (they make many of Forest River's doors), you can call:
Parts & Warranty
Shower Enclosures America
I doubt they made your door if it's falling apart, their products are incredibly well made, kind of puts the RV industry to shame.
Service is also outstanding.
If it's from Irvine Shade & Door, you can contact them at:
1000 Verdant Drive
Elkhart, Indiana 46516
2016 Georgetown 364 TSF
2015 FunFinder 242BDS traded for above
2014 Starcraft 1221 Comet traded for above