With the lens back plate removed, temporarily replace one of the 4 screws which secured it. It will not be possible to drive it fully home; only tighten it until resistance is felt.

Lift out the three zoom motor gears and put them aside.

Lift the lens off the bench and using a small flat screwdriver, gently turn the gear teeth which the last zoom motor gear engaged with until the lens is open approximately half way.

Now feed the two ribbons protruding through a slot in the barrel back into the lens.

Resting the lens face-down on the bench, retract it to the closed position by turning the gear teeth in the opposite direction. Remove the screw you temporarily reinserted.

Follow the reverse procedure for reassembly.