Is it loaded with backing & top separately with the batting floated between? If its loaded as one unit I would say you need to unload and baste well, if it is loaded one piece at a time you should be able to tighten up the backing, smoothing it, then use clamps on the sides to keep them from flopping. Is the backing one piece or pieced? If pieced it is often recommended to have the seam horizontal so it lays flat along the take up bar, when it is vertical it builds up 4-layers of bulk with each turn of the bar making the center big & the edges floppy. As for the batting... Each time you are going to advance the quilt you should be loosening the front ( side you are unwinding) tug on the batting, pulling it straight, wrinkle free, then tighten the backing, checking backing and batting that all is straight, smooth and wrinkle free, then tighten and smooth the top