Hi All, I have a Delta plus with a gas bench and conflo. I recently had a sudden decrease in sensitivity (10x less sensitivity than normal). I checked the reference gases, conflo, gas bench, and source tuning. They were all fine. I then replaced the filament and got the same result. The source should not be that dirty, it was last cleaned 8 months ago. What else should I be checking? Jennifer Eikenberry Assistant Research Scientist Michigan Technological University School of Forest Resources and Environmental Science 1400 Townsend Drive Houghton, Michigan 49931 Phone 906-487-1774 FAX 906-487-2915