Kempe, you need to unscrew the pulley from the axle of the reel. As you said, it is on a left hand thread, because otherwise it would unscrew itself just from the belt drive torque. You have to make a special tool for the job: two bolts of the right size and the right distance apart to fit the holes in the pulley, attached to a piece of flat steel maybe 1/4" to 3/8" thick, about 15" long, by means of two drilled holes. You will have to hold the reel from rotating while you unscrew the pulley, probably with a piece of wood pushed through it (don't use metal, obviously).

[Linked Image]