Unscrew the guts, get a new nozzle and screw and fix it while its in your hand.
Probably for the ten bucks or so a new head costs, it might be easier to just replace the guts with a new one rather than spend the effort it may take to find or make a new screw.

Flush the system or just that zone while your at it.

Just screw a new one in from the top ... no removal is necessary. I did the same thing and use the screw from a broken PGP head to replace it with. When some landscapers tore up my yard, I took all the heads they were going to throw away and stashed them for parts like this.

You can remove the adjustment screw by simply backing it all the way out the top.

My PGP adjustment screw is all the way in and I cannot get a grasp on it to back it up. I have two heads like this. How do I back up the screw?

Thank you Bunkers. I searched far and wide for the answer you provided here. Even Hunter’s website didn’t have this answer.