Ray,
I am not sure about that.
However, a friend of mine did it with
lapping paste, (1ml) using hand drill.
He let the worm to rotate 20-30 times in both directions (careful, you do not want this stuff in bearings), then dismantled and washed the whole thing, re-greased and put together exactly as it was before lapping.
I can't find his post (it was in yah0o group EQ6), but I remember he was tallking about achieving 2-3arcsec RMS.