Insert 6701 Bearing on the Small 3/8' Pulley Gear and align the set screw hole to the other end of the Ulna Gearbox Shaft (3/8' Brass Tube)

Secure both pieces using the M3 Set Screw

Insert the 6701 Bearing on the Big 5/16' Pulley Gear and secure the Pulley Gear to the 5/16' Brass Tube using M3 Set Screw

If the Brass Tube is NOT flushed to the face of the Big Pulley Gear, then that's the wrong end of the Brass Tube

Insert the 5/16' Brass Tube through the Ulna Gear Box

Repeat the First Instruction (Black) of this step with the Small 5/16' Pulley Gear

Notice that the orientation of the Small 5/16' Pulley Gear is Opposite of the first step

Check that when Big Pulley Gear is pushed all the in the output disk of the Ulna Gearbox, the small Pulley gear Bearings are spaced apart correctly, using one of the Tail pieces