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There's no date on this document, but perhaps it will be of use.
This happened to us a year ago on both of our wings while on a trip.
Try contacting Halcyon directly. Within a couple of hours, new ones were couriered to our hotel. No charge, no argument...
My personal recommendation would be to get a well fitting screwdriver to hold that shaft in place (maybe with a helper) and turn the button with a pair of vise-grips or channel locks - mine was easily "dissasemble-able" and I haven't taken it apart in at least8 years (as evidenced by the corrosion on the shaft and metal housing).