17O+3 at FC6 became 550nA.

17O hand valve found to be closed. Probable cause may be the cold weather.

After opening the valve beam came back. 2.6uA of 17+3 at FC6.

Notes by DMG 8-Nov-2009:

This valve is barely cracked. Temperature will affect it at such close settings.

Starting pressure Saturday when beam fell off: 4e-8 Torr.

Pressure today with strong beam: 6e-8 Torr.

Pressure during Saturday setup where beam began to quench: 8e-8 Torr.

Conclusion: Correct operating pressure range for Supernanogan source is tight. We removed the MWS head, anticipating this to be the case. It's so even when the slight extra pressure is entirely due to the source gas.