Finally discovered why air would not stay purged and pressure gauge was so low. The offline chlorine feeder 'O' ring was stretched ~ 1/2 - 5/8" and kinked, allowing air into the feeder. 'O' ring tuck with a utility knife; thin strips Gorilla Tape spiraled opposite directions keeping ends together is working so far. With any luck it may serve 'till a new 'O' ring gets here.
OBC