I work on a 6470A QQQ. The MS was shut down for maintenance, change of oil of the rough pump, source cleaning, AJS ESI needle replacement and capillary replacement were performed.
Rough vac and high vac values are better than before shutting down. Somehow, it can't seem to be able to tune in positive mode. I tried tuning both polarities and it kept failing, negative tune alone successfully finished but positive tuning fails. When in manual tune, low mass seems to be fine but higher mass are either very low (about 1200-2000 counts) or just have no definition. I tried tuning from factory, from another successful tune file, but nothing seems to work.
Anyone got an idea how to resolve this?