i have a 2016 discover 40E and had the same problem after about 2 yrs. i took mattress off and found same thing as you did. screws all over the place. I found a damaged rail and gears. on one side (there are two rails) I had to order new set of rails and gears and i fixed myself. the reason this all happened was poor workmanship from factory. PS took a long time to get parts.