I broke one as well; here's what you do for a replacement; go to the nuts/bolts/screws section at Lowes/Home Depot, and look for the fastener drawers. In the Miscelaneous Fastener Drawer, look for those threaded Shouldered Thumb Screws; they are basically a machine screw with normal threads, but instead of a hex or allen head on them, they have a flat disc that you grasp with your thumb and forefinger(see photo). Then grind off the excess width of the disc to the same width of the thread body and drill a hole in the center of the remaining flat area the size of the mounting screws. The original threaded insert in the wing is Metric; it may be hard to find a Metric Thumb Screw to match, I wasn't able to find one; so I removed some covering from the top of the wing above where the threaded insert would be and replaced it with the proper thread T-Nut and epoxied it in place and recovered that area, works great, no problems.