Using you index finger under the inside top of the rear hull ring and your thumb against the accessory port connector, gently pry the rear hull ring from the main hull. If the rear dome ring binds while pulling the top, you may need to pull the bottom to even it up for easier removal.
If you plan to replace the O-ring, remove it by pinching it around the rear hull ring to create a slack section that can be grabbed. Do NOT use a metal tool to remove the O-ring.
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