Further info: The pulleys are not misaligned (they line up perfectly) the only thing possible is the spring is not powerful enough to keep the idler pulley from bouncing when there is sudden changes in acceleration (as when turning) especially at slow speeds. Also I have no faith in the technicians at Lowes being able to diagnose and repair this condition. I think the spring on the idler pulley is weak. If you could just mail me a replacement spring we could at the very least rule that out as a cause and if that is the problem the fix will cost you less than paying Lowes to muck around and screw something else up.