I love my RH, and have been weaving on it for a couple of years. I've noticed that the longer I weave on the fabric, the looser the outside several inches become compared to the middle of the fabric. I have: checked my tension and tried various techniques to make sure it is correct, used rigid sticks between layers when I'm winding on, used rigid sticks on the woven fabric as it winds on the front of the loom, and now it's happening again on a 22" wide alpaca mobius shawl I'm working on now. Could it be that I'm stretching the selvedges while I'm weaving, and thus making that part of the fabric thinner, and therefore, losing its tension? I can see how that might happen with a stretchy yarn, but it even happens with cotton. Suggestions?