Try this.
Here's what I do to all my threaded inserts, metal to metal threads etc. Get a roll of plumbers PTFE tape, (couple of £'s) and wrap a few turns round each thread before screwing in, this will give a snug damped fit and remove any play and vibrations etc. It has lots uses and is easy to remove too.
Cheers
Kevin.
Technics SL1210 (MN bearing, PH PSU, VDH103), Lenco L75 - to do up. Cambridge 840CA
mplification: WAD6550 With a few mods(Black Gates, Jupiters, Mullards), WD PRE3(TJ Full music), WD Phono3(Full music)
Loudspeakers: Troels Gravesen's CA18RNX