Accelerator pump issues after installing rebuild kit

This has happened three times in a row now, with three different carburetors, you know, the '60's and '70's Carter two-barrels used on small block Mopars. When I am done cleaning, checking, and installing the carbs, the accelerator pumps just don't want to pump anything more than a micro-drop of gasoline. My vehicles hesitant for a moment when accelerating from a stop, and then they take off normally. ('65 Valiants and '72 Satellite Sebring Plus)

I know there is a certain size check ball that is placed in the bottom of the well, I know one can adjust the pump shot, and I know to lubricate the leather with oil, tranny fluid, gasoline or something beforehand. I have posted this problem before and even sent a message to Slant Six Dan, but I have never received an answer. Am I the only one with such bad luck? Thank you for listening and responding if you have some tip. P.S. I actually found a 1973 NOS Carter carb online (had never been installed before) and after changing out all the gaskets in that carb, I STILL had accelerator pump failure.