Interesting... did the machine fall over?
Regardless, your machine is the 12-1/4" drill press. That pinion retaining screw is shorter than the retaining screw on the larger 13-1/2" and 15-1/2" drill presses. I have a couple longer screws, but not yours.
The issue with those screws is that they are a proprietary part; you cannot buy one off the shelf.
The groove in the pinion shaft is 0.195" wide.
The dog point on those are 0.188" diameter.
The dog point on a standard set screw is 0.203" diameter. So it doesn't fit in the groove.
HOWEVER, it's easy to grind/sand the dog point on a standard set screw to fit the groove. I made this one in just a few minutes.
It fits and works perfectly with a jam nut.
You can make your own, or I can sell this one.
If you are refurbishing the entire machine, I also have a refurb hardware kit available.
https://www.garagejournal.com/forum/threads/craftsman-drill-press.227480/post-11436471
If you're interested, start a private conversation with me.