I don't really know how to explain it otherwise... It seems to only happen with arlon 3420. I only have arlon 3420 and dol1460. I can go 150' of the 1460 without any shift but the 3420 also seems to bunch up on the right side so I use my hand on the roll to increase the tension and then it walks. Is there an adjusment within the laminator that maybe needs to be fixed or should I try some different cal lams? its workable, not so much on long runs.