I would try using a wood nail, heated in the torch flame, or a soldering iron to melt some of the base plastic back into those holes. It's likely polyethylene or polypropylene, both of which are used as the BOTTLE for the other glues--nothing bonds to them.

If you try your standard plumbing-pipe ABS solvent and that works, then you can cut off "excess" material from elsewhere on your bracket and solvent-bond that over your holes.

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James Marriott
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