Sear sets only with the safety on fire.

Will not set the sear on half safety which is a PIA, IE like when I loaded a shell in the hunting stand last year and did not realize it
was on half safety and the sear did not set, so you know what happened when I pulled the trigger.

Nothing.

In the trigger the part that moves is sort of locked in under the trigger when on half safety.
I can get it to work if I loosen up the safety adjustment screw too much.

I have had this trigger for a long time and could swear I had it set up so that it set the sear on half safety before, but now for some reason I cant figure it out. That may have been on another action though. I have had it on several.

Right now it is on an older flat back.