oldsewnsew

I pulled the needle plate screws on a 201, and I get #8-40.
Here is a picture of some tools used with threading.
[ATTACH=CONFIG]470785[/ATTACH] From the left is a die handle, for cutting or cleaning (chasing) threads for a screw. 2nd is a die for the same. 3rd and above it are tap holders, which hold the 2 packaged items. The red/white package is an 8-32 tap, pretty common, except on sewing machines. The yellow/green package is a #1 easy out, which needs a hole at least 5/64" (between 1/16 and 3/32") The tip of it would probably hit the interfering part before it gained any purchase on the bushing. Between the 2 packages is a thread guage, this one for metric fasteners. Taps and easy outs are a couple bucks a piece. The thread guage, maybe $7 or 10?
Machine screws have a defined outside diameter, what mostly varies is the number of threads per inch. (TPI) So a 6-32 screw has an outside diameter of (6 x .019) + .062= .176". It has 32 threads (teeth) per inch.
Hope this wasn't too boring!
So now chasing threads has another meaning for ya