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The gunwale mounted fasteners for my bimini brackets are pulling out. The existing hardware consists of a brass cylindrical threaded insert (1/4-20 or 10-24) that fits tightly in the barrel of a a rubber grommet. With the grommet in the deck hole, you tighten the mounting screw, and the rubber underneath compresses and folds over, which prevents the threaded insert from pulling out of the hole drilled in the deck. There is no backing wood, only foam under the brackets. Age has taken its toll however, and the rubber is disintegrating. I've never seen this type of blind threaded fastener before and am having a difficult time finding a direct replacement. I've considered stainless toggles, but am concerned about the size of hole required, and the need to gouge out a lot of foam in order to give the toggle room to spread once inserted. Has anyone used a better mounting scheme?
Jim