Step 8.
Very Important: Finish one entire side of the hand BEFORE REPEATING STEPS 7 & 8 on the other side.
Attach the Side Rigid Digit.
Attach the Side Rigid Digit over Geared Digit and secure with 2x Two Bolts.
When the two parts are joined properly, carefully screw in Side Bolts.
Check:
Test the movement of one Geared Digit. If it moves smoothly now is the time to REPEAT STEPS 7 & 8 for the other side. Be sure the Side Bolts are tight.