11. On the Vacuum Control Panel, to the right of the stage, you will see a key.
- Turn the key to MAN (Manual Position).
- Then switch the Diffusion Pump Switch down.
- Let the diffusion pump cool for 20 - 30 minutes.
- (The Diffusion Pump is the big green thing beneath the spectrometers. Walk behind the probe and open the tall side door to see it).