We have a 5977 that we use to analyze oil samples primarily in DCM or hexane. We have been having an issue with our tuning degrading rapidly after cleaning the source (our latest tune file is attached). EM volts are at around 1800 directly after cleaning and then quickly (in a matter of 1 week) the autotune produces an EM volts value as high as 2600. The repeller is also maxed out, although this does not seem to change after cleaning the source. Our autotune peak shapes look very jagged for 219 and 502, and the relative abundance of 219 keeps falling as the conditions deteriorate (it is now at 4.8%). Over the course of a run (of ~30 samples and standards) the sensitivity drops off markedly. It does not appear from the air and water backgrounds that we have a leak. We have replaced both filaments and cleaned the source twice. We have observed this behavior after both cleanings. Has anyone had a similar experience? Thank you!