"Roy" wrote: (clip) It would never ever break justy keep stretching and
welding itself to each other on the spools, (clip)
^^^^^^^^^^^^^^^^^^
I have given up on all the self-feeding spool systems. Not only does the
string weld to itself inside the spool--it always breaks just at the feed
hole, requiring the spool to be disassembled and rethreaded. I now use the
types of cutting head where you cut off several inches of string and stab it
into the holes. You can use heavy string that way, which lasts longer, and
you can replace the worn or broken pieces in seconds.