quite a few years since I bought it and I don’t remember anything about it.
but you still have it and 'could' make a foto, right? just to mention. i had this prob very long ago.
i guess leaking could be because the specific pens could have some different behaviour. while the ink flows down, air must flow into the catrige. if too much air can flow in, i'ld guess thats when leaking occurs, but letting that tiny amount of air that precisely into the catrige might be possible, for a refueled catridge, but could be more error prone due to moving parts or just might not be the same needed for every pen that fits and the vendor chooses somewhere in the middle to "fit" more pen types, but that was guessing from long time ago. however now that it seems that this prob still exists3.... maybe you can make a photo of the catrige and the pen.
you're welcome.
what i'ld suggest... a general rule that i like to always follow is to use a test system for everything new. but that does not need to be a full separate system every time.
lets say you have your mailbox and want to try getting new mails from it using fetchmail. first you can use uidl mechanisms to only fefch every mail once and besides that leave them all on the server, but i like it a bit more secure: create a second email adress/account at your mail providers service only for testing. thus you can do whatever you like to to test the mechanisms only without even touching your real inbox (maybe even fill it up with large emails and look how the system reacts, i once had an email account with a cheap provider that deadlocked the inboxes when full..). then when everything is as you want it, switch the account and password (or create another config file for fetchmail) and your're done. every change (not only fetchmail things) could go tested this way before going live with the changes. filtering could be done with procmail for example, but when the mda that is called by procmail somehow exits with success when the email really isn't delivered, then the email might get lost forever depending on the settings of course. so fiddling with new stuff always carries the risk of not fiddling correctly ;-)
have fun !