Something doesn't add up here. If the bezel is snug going on, then loose, do you mean it's loose on its retaining ring?
Or is the retaining ring snug going on, then loose?
If the bezel is a loose fit on the ring, just add some bumps to your spring washer to eliminate the gap.
If the ring is loose over the crystal, see if the watchmaker can compress/size down the ring to a smaller inside diameter, then polish the sidewalls of the T39 crystal to square it up until the ring is a snug press fit all the way to seated.