Sand-blasting cabinets?

Could be somethng in the pickup tube."Burp" the blasting gun. Asuming it's a siphon feed gun you can place your finger over the nozzle while squeezing the trigger.THis will force all the air into the pickup tube and clear any clogs out. Do this until your sure the pickup tube is clear and try again. Also make suire there are no kinks in the pickup tube line and that it's not collaspsing.I ended up replacing my tubes line with heavier stuff as I was having problems,but now it works great!