Another view of the parts. The black O-ring goes in the groove above the threads to prevent the plotter vibrations from unscrewing the pen top. The original ball point pen cartridge is also shown in this picture.
Feel free to contact me, David Gesswein firstname.lastname@example.org
with any questions, comments on the web site, or if you have related equipment,
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related, computers, peripherals used with them, DEC or third party, or