I am taking apart a Dictator Pen. The filling system is an aeromatic style but I can find very little on the web about its particular configuration. What is the most likely way I can remove the sac guard to replace the sac? Any ideas?

In my experience, most sac guards are friction set on the section. I've seen 1 or 3 that have been threaded, but those were the exception to the rule. Just give it some heat, and a firm wiggle & pull. That should get it off.

Good luck
POE

oops....