[PaulR]

As a matter of interest the hedge trimmer handle is used to unscrew the flat driver. There is a slot in it which can be seen in the first picture. The flat of the drive fits into that. You then give the handle a sharp tap to loosen the drive. I used one for years until the gears in the trimmer attachment wore out and, yes, it was heavy and didn't have the instant stop feature of modern dedicated hedge trimmers.