Before putting this thread behind, I would like to touch on drilling the screw if required as referenced in post #4
For most, I suspect drilling a .8mm to 1.0mm 18s dial screw is perceived as challenging to say the least. I also suspect the thought of drilling the hole down the center of the screw creating no damage to the thread, can be considered a nightmare. However, this depends on how it is accomplished.
At the very least to be successful, you will need a precision drill and a way to hold the movement and or movement plate. Personally I use a small Milling machine that is far more versatile and controllable as a precision drill. Ironically, the small mill is often less expensive than a quality precision drill.
The first photo shows a movement being held by a Lathe chuck mounted in the Mill. In this case, the chuck holds the plates to protect the dial rather than being held in a vise that may damage the dial.
From this point I have mounted a gage pin in a WW collet the same diameter as the dial screw head. This in turn is centered on the screw head under optics thus centering the spindle in relation to the screw. Second Photo.
At this point, the screw can now be spot drilled and then drilled. However, the slot in the screw can easily deflect small standard spotting drills causing the spot and drilling process to wander off of the screw center and often damage plate threads.
We are very fortunate in todays world to have all of the readily available tooling that in some cases was not available as recently as five years ago. To resolve the spotting issue, a carbide 60 degree Mill Drill has never failed to produce a centered pocket under the most adverse conditions. An example per attached link.
1/32(.0313) 2 Flute Carbide 60 Degree Drill Mill
Once a pocket has been machined slightly larger than the drill to be used, the drill has no choice but to drill down the center of the screw. Centering is the most important part of successful screw drilling. When drilling, the "Z" axis hand wheel calibration can be used to control drilling depth so as not to drill into the dial post. Drill sizes can be increased ever so slightly until the screw thread can be plucked from the plate threads.
Jerry Kieffer