Well took it out of the box. First contact with the seller wasn't that helpful. Inspect they said. As if I knew what I was doing!
First thing I notice is the backlash. It's about 0.45 degrees, or one hole on the 20 hole plate. If I understand how to figure this out, it is: 360/40 * 1/20 = 0.45 degrees. I don't know if this is typical, or not. (Damaged or not.) There's some obvious additional polishing needed, the handle does not adjust freely as the slot seems to be non-uniform width, or there's some burrs. That I expected. At least for several rotations of the worm, there doesn't seem to be any sticking - but I have not done a full 40 rotations.
The instructions say to reduce worm backlash one does the following
1. Loosen locking bolt and turn the stop screw so far until worm backlash is taken out.
2. Tighten locking bolt.
The worm backlash has been removed when no more play can be observed on the index head spindle.
Of course the terminology used does not match the parts list nomenclature. Why do manual writers do this? New users don't know the synonyms yet. Old users don't need the manual... The picture next to the text (page 3) is fuzzy. Found a long winded youtube video, think I know how to adjust it now. Just needed a clear picture.
Guess I'll be doing at least a partial tear down.