We know about the dumb things owners do to their saws, how about trimmers? There are probably more of them in urban centres than chainsaws and the owners never seem to understand how to load the line drum with new line. With the common bent shaft trimmer the line head turn in the same direction as the engine, and with the bump-to-feed system the knob holding the spool in the hub is attached with a normal right hand thread but with the straight shaft trimmer with a gearbox (not the tendon), the bevel gears reverse the direction that the line head turns so the knob is fitted with a left hand thread. So a guy with a bent shaft model decided to buy a better trimmer with a straight shaft and of course, tried to remove the knob the same way as with the bent shaft and turned it hard enough in the wrong direction until the plastic stripped and the knob was free to turn in any direction. Couldn't get the spool off, sold the trimmer for parts.