In the past our HTT was always covered in the winter even though it's undercover 24/7 and we never had any moisture get into the awning. This past winter was the first year for our TT and we didn't get the ADCO cover, trying to give the budget a break, and also knowing it was undercover and should be fine. The TT was fine....the awning was a MESS. Being undercover, there was no way rain could have gotten in, so it had to be condensation. Although others have used bleach or bleach cleaners, we just do not like the idea. The regular car wash soap didn't touch it. Black streak remover, no go. We tried some Dawn in the wash water and still no good. Simple green no improvement. We finally resorted to our "go-to" cleaner, the LA's Awesome Cleaner (the yellow color one) from the Dollar Tree. Did not dilute it, but used full strength with a soft, long handled brush. It took several wash/rinse times, but it got it all off and you'd never know it was there. Summer hasn't been a problem, but the winter dampness got us.
IIRC, someone either here or on Hybrid Explorer made a cover for the roller out of PVC pipe - got a size larger than the roller, made a slot to allow it to go over and it helped. Would think that if your problem is condensation in addition to rain, you might be able to fashion some sort of waterproof fabric to enclose the ends and maybe stop this. This would be a relatively simple and inexpensive thing to try. Other than that, you might check with a canvas shop/boat canvas/upholstery shop and see if they could make a cover for the roller. The glitch might be in securing it, but maybe worth checking into. Good luck. We're going to invest in the cover for the TT this year.
Trailerless but still have the spirit
2013 Rockwood Ultra Lite 2604 - new family
2007 Rockwood ROO HTT - new family
2003 Ford F-150
4 doggies - We support Adopt/Rescue.
Sam, you were the best!
Cubbie, Foxy, Biscuit and Lily - all rescues!