Rodney that is one half of the hook drive gear set, the half that actually drives the hook. The other half is steel and on the horizontal shaft that the cleated belt drives. The pic is showing it from the back of the free arm. If it only had one crack I wouldn't be so concerned, but it has 3. I've been told to just use it til it breaks, but I don't want it to break. Sniff.
Cari