Sapper - part of the issue is people confuse brushcutter with whipper snipper and flog the hell out of them - slam them into 3 ft high grass - head slows down then the engine puts too much torque on the flex line (effectively braided wire) and twists it - kink or snaps it.
The flex line has to turn in the curved shaft - extra heat, friction, wear. should remove it occasionally and regrease for long life really - usually 1, 2 or 4 bolts holding the shaft on.
Straight shafts have solid drive rod that drives the gearbox. Some have the flex line (like cheaper Ryobi), but as it is straight through there is less friction
I have a Talon here with one of the orbit trim metal heads - owner used it 2 times and kinked the cable, then a victa tornado which just plat out snapped - would take a photo to show you but it went in the last tip purge (the shaft that is - kept everything else).
By the way, the bolt thread on the bump heads is designed to tighten under turning of the shaft - so straight shaft bump heads unscrew the other way (as the gear head reverses direction) - so the likelihood of flying off is less. Something Mcculloch should have known - their blower almost killed me when the mulching blades shot out due to the bolt undoing when revved.
Norm, I can help with the fitting - I remember I have a Homelite HLT26 which has had a yellow aftermarket manual feed fitted - it has a sort of spacer cone with a simple bolt and washer holding it on - holds strong.
Will look for it tomorrow
In the mean time, the speed feed come with these things that screw into the ryobi thread, then you could screw the nylock onto the end - maybe use something like that.
