John Deere S1400 weed eater string spool issues

[nickel plate]

Either I'm not doing it right but I have virtually ground down the original "bump head" spool. The string tangles up internally like a casting fishing reel's "birds nest" constantly. Short of schooling me (please but optional) on how to wind the .095" string on properly and not destroy the bump head by banging it into oblivian, is there an aftermarket 8"+- two string head made for this model? The type when the two 8"+- strings wear down you shut it off, pull out the old worn down two string nubbins and replace with two new 8" strings.
The steel or composite blades are not an option as we have a lot of rocks and dry brush-don't want to start the forest on fire or blow up on the rocks a pricey set of rigid blades from the get go.