Thanks for the guidance so far. I put on the optivisor, used a bit of profanity and got it sorted out.
After removing the safety I see why the middle position doesn't positively engage.
The safety detent plunger has worn down the "ridge" of metal between the fire & middle position detents.
Attempted using a Tilden safety but it turns very stiffly & the plunger will not positively engage each detent. The plunger is wearing the same ridge down as on the original flag safety & it will not pass a function check when reassembled. Reinstalled the flag safety and it functions as designed.
I've read the Tilden was designed to be a "drop-in" replacement. For those who've installed them, do some require fitting to make them function correctly?
