I can second Jeffs experience. I pulled my synchronizer gauge apart. Had to gently unwrap the metal bezel with a little screw driver. Its hard to do without breaking the glass and putting it back together without it looking all mangled is also a trick.
If I had more gauges to clean I'd either live with it or buy new.
Just my $0.02.
-K
1986, 32' Sedan, twin 360ci, 275hp Chrysler's w/ K&N flame arrestors