We have a QBB13 and the cushion/bed part pulled off ours too. Hadn't even been used as a bed but we kept finding bolts on the floor after travel. My husband a piece of 1x3" hardwood at each end where the frame bolts into the base and used glue and self tapping screws through the hardwood into the base and then used self tapping screws to fasten down the frame of the bed. It was a pain because he had to remove the cushions from the frame so he could install the frame. But it's firmly in place now and our granddaughter slept on it for several weeks in our last camping trip and it hasn't loosened at all.