Shade Tree Mechanic's Way
I would put a light coat of Vaseline on the Pin.
Then put super glue gel in crack as far down as I can.
Then screw them together.
Then tape the collar tight with masking tape.
Pray that you can get it apart later.
Shop Repair
If I had a Lathe I would put very thin epoxy in the crack then wrap tape around it, then clean up the threads.
Dude...please stop. DO NOT use superglue to repair cracks in cues.
Take that one to the cue makers while you are asking about growth rings. Ask them what they think when they get cues in that have been repaired that way.
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