Pumping an Agilent 5977 GC/MS back down after maintenance is the moment you find out whether everything was put back together correctly. In this video, I show the pump-down process after the MS has been opened for maintenance. I go through: • Closing the analyzer and establishing the initial vacuum • Starting Pump Down in Vacuum Control • Watching the foreline pressure decrease • Monitoring the diffusion pump, source and quadrupole status • Confirming the system reaches READY