The side the roller gears are on always seems to want to roll tighter than the far end, l've found...the longer the bars, the more this is evident. When l float, l left and floof the quilt top only with each advance, then smoothe out and baste sides from belly bar to where my previous basting begins. Next, l use clips on the belly bar, then attach side leads. If the backing is thick ( flannel, etc., l mount that on lower bar ( meant for the top) so the clips can secure the belly bar nicely. I keep a water bottle handy for easing fullness on any problem areas ( you should never try stretching what's next to a poufy area). Sometimes the can of starch comes out too, if need be. I'm a volunteer quilter for QOV, and have all types of skill levels sending me tops. I always get them off the frame squared/ even.