ma, bought a new weed eater / trimmer. so picked up some line for her, and filled it up. not even 5 seconds. and the odd shape line, got caught up in the bump head to auto feed more line out.
redid things up. not even 7 seconds, and that was it.
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now a week or 2 later. redid the odd shape line, and have not had a single problem with it. exception the stupid "razor blade" / sharp edge. to cut line that ends up to long. that is a different story, and will not cut round or odd shape line.
when i redid the odd shape this last time. i "loosely" put the line. not so loose that it would unravel. but not so tight that i was physically pulling on the line to get it nice and tight as i put the line on. just tight enough to keep it unraveling.
i also took extra care, to make sure lines wove better. vs just randomly bouncing the line all over the place, as i put it on.
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now that i have said above. watch it happen, weld up and get all caught up inside the bump head several more times every time it gets used again.
you might try "less" string, vs trying to put as much string as possible on the bump head of the trimmer / weed eater. maybe ya packing things to tight. and simply not enough room for things to spin and let the line out with out getting all tangled up.
other words to above, kinda like a winch. were you just pulled all the cable out and now winding it back in, without any sort of load on the cable. and the cable begins to wrap itself up over to one side, vs a nice neat spiral. *shrugs*
most likely it will always happen some, with odd shape line. just do to the nature of it being odd shape, and catching the rest of the line in the bump head of the trimmer.