1968 340 AVS 4425S carb problems

The 1968 AFB originally had the one idle mixture at the top (another brilliant idea for smog control). When delivered they idled like crap! So we knocked out the lead plugs to reach those little idle mixture screws that you see. I don't think that hole is threaded all the way, at least threads may not have survived the process. Originally they would then adjust well. I have a '68 AFB that I have restored and yes- those little screws can become frozen. I had to get another carb as I wanted to be original.