Screw

The Toro 620 models shear pin are hard to replace. Once you get broken pin out you need to tape in the new bolt so when you turn the rotor to opposite side to but on nut with long nose pliers the bolts won't fall out. Long extended sockets needed on both nut and bolt end
Good luck

Removed the old shear pin and nut
Put new shear pin and nut in.

1.tipped the blower back until handles were on the ground.
2. Rotated the auger shaft by rotating the impeller until the bolt hole in shaft was in a workable position, then pushed out piece of the broken bolt that was in the shaft.
3. Inserted the new bolt from bottom side and started the nut. This is the awkward part because the bolt is within the auger hub. Snugged down the self locking nut.
4. Returned the blower to its normal position. Started engine and tested the auger for proper action. DONE.
5. IMPORTANT: Ordered 2 new bolts and locking nuts from ereplacementparts to have on hand if another bolt shears.

1. Made sure the snowthrower off and had the sparkplug unpluged.
2. Tillted the snowthrower back.
3. Used a 3 1/2 exterior screw to push out the remains of the old pin.
4. Inserted the new pin and nut.
5. Lowered the Snowthorower back to the ground.
6. Attached the spark plug.

Inserted shear pin then put the nut into a socket to seat it then tightened it with a little play not super tight.