The finder screws for the 140 and the screw that holds the sun projection rod are not the same size. The finder screws are smaller. However, the finder screws on the 152 finder are the same size as the projection rod screws.
I checked my 152. The finder and rod holder screws are the same thread (10X24) but different design head and length. These screws are plated brass. Stainless steel is a good match for color. I think a standard 10X24 hex bolt will have enough head material to machine a match.
Head diameter 0.471"
Serrated edge 0.091" wide
working thread length 0.375"
There is some curved detail from the serrated edge down to the threads. I'm not attempting to blue print that. I suggest getting one to copy that you can send back to a lender. A stainless copy would be superior to the originals. Your nickel plated brass ones are broke, you'd probably break the bracket before a stainless screw. Stainless can be ground and sanded but is harder to machine with standard cutting tips. Stainless is 'chunky' to machine in a regular manner.