Not clear on how to adjust pot pressure blaster

The media valve controls the rate at which the blasting media is fed into the hose-nozzle. Too much media and it will not move through the hose to the nozzle. Too little and you are just blasting air.
The choke valve balances air to and through the media with air directly to the nozzle. With my pot blaster you want some air going to the pot, but most of it feeding to the nozzle.
Regardless of where the air pressure is, with my blasters, cabinet and pot, the biggest contributors to getting the media to feed without blockage in the hose is having really dry air to the blast system and really dry media.
When I blast with sand, I dry it prior to using in the oven using a couple of large turkey pans. A couple of hours at 275 F with a couple of stirs. The black beauty blast media I do not dry. But I sift it to remove the sand, fines, chips and chunks of what was blasted free.