I'm not real good with these, but when the same thing happened to us with our 2nd 5th wheel (3 Slides) there is a little lever at one end and they say its suppose to take up the slack when the lever is triped, Please forgive me, i don't remember what the brand of covers they were! Sorry, i hope i might have been of some help to you!
Doug & Darlene Morgan RVM96 & Abby Gabby(pooch)
04 Dolphin 6375 LX W-24 Chassis #434136
"The Journey is our Destination"Hickory,NC