23-09-2022, 11:34 PM
As noted, setscrew 8 is to lock the column 15 but a single fixing only gives a quite coarse adjustment of one notch so a second screw at half spacing would be an improvement.
If you are happy with the worm position adjustment, with no up and down movement, then do nothing with the second hole.
If you are happy with the worm position adjustment, with no up and down movement, then do nothing with the second hole.