I've accumulated a few of these over the past 20 years. I made the mistake of thinking the section would come away like any other pen and ending up fracturing one that I had to send to Victor at Penopoly a long time ago. I can't remember what it it actually was - i think it was a metal connector with longitudinal ridges that should have been pulled out directly instead of with a twisting motion. I tried to look it up in Da Book but that basically says there are many different ways the section should come away.

I was always leaving these as retirement projects but having unexpectedly won one from the auction site recently, I am somewhat inspired to try a bit early. Does anyone have advice/experience to share please? I last changed a sac maybe 15 years ago.