I tried again using the metal hooked piece from a binder clip. (Kind of an "L" shape.) Pried a few times then POP!! Off it came.
Regrettably, a chunk of the ceramic came off too. Can't find it -- it flew past me. But you can see the jaggedy edge where it broke off.
There are in fact two notches in the filler ring. If I intended to put it back on.
I've been
vaping this particular E2 cart for a couple of weeks non stop as my sole
vape. I have now consecrated it to the trash and broken out a new one.
Filled it with Liquid XPress' "Spicy Ice" and
vaping away happily.
Perhaps I'll perfect the ring removal with more practice. For now it seems best for the well-being of my carts to continue with the syringe refills.