I buy and use mostly Echo commercial trimmers because I like them, the employees like them and the SRM style spools are so easy to keep extras loaded and in the trucks and change out. Well two weeks ago I also changed all of my RedMax heads (2500's & 2600's) to the Echo SRM heads so that we could keep only one type of spool loaded and on the trucks to cut down on line change time. Well the line (all the same brand) is welding bad on the RedMax trimmers, so bad that it "jams up" but not doing it at all on the Echo's. If we switch the spool out of the RM and put it in the Echo again it does fine. I have sprayed them with WD40 and it still welds every single time. Anyone have any idea what would be causing this? Thanks!