Headset problems

Thought I'd resurrect rather than start a new thread.

Bottom headset cup on second hand frame is loose - Doesn't drop out on it's own, but can pull it out by hand. think it might be a JIS/ISO missmatch 30.2 mm vs 30.0 Any options - Heard mention of loctite/glueing it. Really don't want to have to shell out for new headset and fitting etc.

As an alternative to loctite.

Use a centre punch and a small hammer to make an even series of punch marks around the internal periphery of the frame where the cup sits.
This will have the effect of decreasing the diameter slightly, when the cup is pressed in it will deform the punch marks to make a tight fit.