Hitachi TM3000 Instruction Manual page 224

Spacer is used to adjust the image brightness.
Cartridge
filament
Figure 5.1-16 Replacing the Cartridge Filament Spacer
Fasten the Wehnelt onto the cartridge filament clockwise. Incorporate it into the electron gun
by verifying it that there is not play. Align the guard ring pin with the holder groove of the
cartridge filament, and insert it vertically.
Holder groove
Figure 5.1-17
Wehnelt and Cartridge Filament
Figure 5.1-19 Inserting the Cartridge Filament
If broken:
Guard ring
Figure 5.1-18
Cartridge Filament Insertion Inlet
5 - 7
Reuse (Wehnelt)
Discard
(Cartridge filament, spacer)
Pin