Remove the 3 screws and nylon bushes running in tracks around the zoom zoom ring mechanism.

Note how the nylon bushes sit over studs in the body.

Not the 6 screws with bushes in the upper section.

Remove the recessed screw with the metal collar holding the zoom ring mechanism. This is the one that transfers torque to the internals.

As can be seen in this picture, the nylon bushes may be fractured, so be gentle.

Now that the plastic zoom ring is loose, rotate it until the metal studs on the body (that were holding the 3 screws and bushes) fit into gaps on the ring allowing it to be lifted off.

You may want to re-grease this on reassembly.

Screws: 3@ M1.6 x 3mm Wafer head (Black), + 1@ M1.6 x 4mm Wafer head (Silver)