carter avs question

Hey everyone,
I have a couple of questions about my Carter AVS carburetor. It's from my 1969 Dodge Dart Swinger with a 340 c.i.
My first question, I am rebuilding it and my diagram shows two "idle mixture screws and springs" at the base of the carburetor and a "by-pass idle air adjustment screw and spring" slightly higher and centered from the other two screws and springs. On my carburetor, the two "idle mixture screws and springs" are not there, they are plugged. Are they supposed to be plugged? Was this done from the factory, or was this done by someone after the car was purchased? The number stamped on the front of the base of the carb is "K8 4612S" if that helps.
My second question, while I was disassembling the carburetor for cleaning I broke one of the two brass screws on the secondary butterfly blade (not sure what it's really called, hopefully it's clear enough what I'm talking about). Is there a place that has replacement parts, specifically this screw? I've searched all sorts of carburetor parts websites with no luck. I'm trying not to have to buy a donor carb for one little brass screw.
Any help would be greatly appreciated.

Thanks,
Konrad