....

Just curious. Why would they use such a soft metal for
that key? I guess it's intended to shear if the flywheel
jams up, but I cant see why the flywheel would jam. If
anything will jam, it will be the blade, but not the
flywheel.

Mark

If the blade hits an immovable object, the shear pin will go
rather than the crank and many other parts, plus it'd probably
bend the shaft in the process. You really should get the right
pin back in it. Same as the shear pin on an outboard motor if
you're familiar with that.

Pop