If possible, try to work in an environment with minimal dust. The goal is to try to avoid dust from getting inside of the lens as much as possible.

Remove the two Phillips #000 screws on the side of the lens mount, holding in the contact assembly.

Next, unscrew the four Phillips #000 screws holding the lens mount onto the lens.

Carefully lift up one side of the lens mount (side opposite of the lens contact). Push the black plastic cover out of the lens mount. Take note that there are four plastic clips around the cover. These clips can break easily if you're not careful.

Be careful when lifting up the side of the lens mount. The lens contact is still attached to the lens mount with a ribbon cable that is attached to the main PCB board.

Push the lens contact off of the metal lens mount and set the lens mount to the side.