Hello Herb
Is the pneumatic piston running smoothly? Air pressure drives the downward
motion of the ref gas capillary (and the upward movement is by spring
return). I have had the piston or airways become partially blocked which
gave rise to raggedly rising ref gas peaks as the piston struggled to move
into position. I had to remove the actuator and blow it out with compressed
air to remove blockage.
Cheers
Robert