HF sandblaster

On my glass bead cabinet under the tip is a nozzle that control air flow. It wears out and goes too big. Once I change that out and verify the ceramic cup is with in spec my machine works great. I’ve tried walnut shells and really had bad results. Went back to glass bead. Also make sure the pick up tube does not have any holes in it. They wear out from the inside out. You may be dropping your level and sucking air.