Be careful with those screws. If your carbs are very old and the cork gasket are hardened, you will break the brass screw. Then you are in trouble. I remove lots of those in carb restoration. First I remove the hardened gasket with a pick. I now have a lathe so I’ll make a special tool to clean them out faster, but a needle pick will work. You may need to soak it first in wd40 or carb cleaner.
So the cork gasket is the only issue ?
And once you get that out the screw usually is free?
Or do the threads need to be lubed up too ?
I have an old set and am getting ready to flog them.