Firm Detent

Removed the too-long, too-narrow 3/32" roll pin from the "selector" on Tonya and replaced it with one of the 500 M2.5x10 spring pins I ordered for the purpose.

The lack of diameter in the pin caused the "selector" to be loose on its shaft and that let the safety rotate the "selector" when they're supposed to move independently of each other.

This is a cosmetic deal, not a functional one since all three positions of the "selector" select semi-auto.  On the 'C' setting the disconnector lacks the shelf for the pin to hit and the pin is ground off; so no full auto.  On the 'S' setting the entire gear set is removed; so no 3-round burst.  In both cases, the auto-sear is missing, because my semi-auto receiver doesn't even have a hole for its pivot pin.

Pics of the "selector" in "action"

S for 3-round burst aka semi-auto

P for semi-auto.

C for full-auto aka semi-auto.

With the "selector" firmed up, the ball detent actually engages the little divots in the receiver!  It's satisfying.

I will say it again, the scope mounting rail on the Tantal is a complete afterthought.  When it's absent, removing the selector requires no tools.  With it present you have to have a long 2.5mm punch and drive out the spring-pin to separate the lever from the shaft.