Depressurize the machine to atmosphere (0 psi). Lock out the air supply. Remove the inspection door. With a small pipe wrench, unscrew the vertical nipple holding the pop-up valve. Once the nipple is removed, you can remove both the nipple and pop-up valve through the inspection door. Inspect:

• Sealing o-ring (CC 02013) — replace if cut, flattened, or hardened
• Pop-up seat — should be smooth, free of embedded media
• Pop-up stem — straight, no scoring

If the sealing o-ring needs to be replaced, you can remove it using a flat-head screwdriver or channel-lock pliers. 

• The o-ring is fully seated into the weldment
• The pop-up valve is aligned with the opening on the top of the machine. To do so, with your hand move the pop-up valve up and down a few times and inspect how it seats with the o-ring. It should fully seat without snagging or binding.

With a No. 6 nozzle at typical abrasive consumption (~750 lb/hr), a 6 cu ft pot loaded with coal slag (~100 lb/ft³) holds 600 lbs of media and runs roughly 45–50 minutes.