Tuning Need help with part

As stated need source for part #18. Cocking pin broke off. On back order at Pyramyd air. Aa s200 .
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Go to Harbour Freight and buy a set of LFET-HAND Drills. The spiral is opposite of a normal drill and they cut in REVERESE. Select a drill smaller by 1/3 from the broken bolt. Punch a small divot in the center of the broken end of the screw (this will help keep the drill from walking) Using a drill on a SLOW SPEED and in REVERSE, add a drop on oil on the divot and slowly drill into the broken bolt. Eventually it will catch and unscrew the broken bolt out of the hole. Go slow, keep everything lined up and you'll be ok.

I am however not of much help in sources for your part but it's likely something standard or barely modified.
 
I used to machine the top of the broken bolt with an End mill first then use a small center drill. Then you don’t have to worry about the drill walking.If you had access to lathe That could be done. I would just slowly plunge the end mill straight into the broken Bolt.And if it’s locked tighted , You could put a little heat to it before using an easy out.