Help! Safety Selector Problem

[montana]

Here's where the detent is... If I take the detent out and hold it vertical it works fine.

I would guess the selector grooves for the selector lever detent were machined out of spec. Do you know who the manufacturer was for the selector lever? If you could get another selector lever to try it would answer a lot of questions. If the selector works without the detent in this would be my best guess.