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I was actually thinking about thread glue
Bearing fitting grade Loctite will do wonders, as long as you don't mind having to get the hot air gun out when it needs dismantling.
I'd be tempted to try extra slots before anything else, it will make the contact pressure more uniform and spread it over a greater area. Think expanding mandrel, but with all the slots at the same end rather than alternating
Have you tried grip paste?