Just to poll the newsgroup, I have found a couple things that make weedwackers work well. #1, do single wound, not double wound string. i.e. only wind one roll of string and one piece coming out of one of the eyelets. Leave the other end wound on top of by the wound string you are using. #2, I think the smaller string welds and binds because the inner spool, outer spool, and then the string gets hot when you use it for a long time. So, dip the spool in a bucket of ice water for a couple of minutes if it's hot outside or you're using it for a long time.
Anyone had similar success with single wound string?