Waters Autospec Premier Operator's Manual page 208

To remove the ion chamber
1. Remove two 12-mm ceramic spacers from each top ceramic rod.
2. Remove two 14-mm metal spacers from each bottom ceramic rod.
Caution:
so that the source lens plates and supporting ceramics do not fall
apart.
7-50 Routine maintenance
12-mm ceramic spacer
Hold down the ceramic rods when removing the ion chamber,
14-mm metal spacer