I have been using a syringe and a blunted needle to fill my converters which is a real convenient, less messy way to do it. And I did that on my Prelude when I first used it. But today, i tried to fill it with the syringe, and some odd pressure phenomena occurred. I put the needle into the virtually empty cartridge, but when I pushed on the syringe, the ink would immediately come back out of the top of the converter. It was as if there was some pressure differential between inside (high pressure) and outside (lower pressure) the converter, but even screwing the plunger back and forth did not remediate this problem. I filled it the old fashioned way with no difficulty. The Sheaffer converter has a narrower hole than my others, but can anyone explain what is going on, particularly since it used to be no problem? thanks.

Ideally the needle should be inserted very gently until its blunt tip is very close to the far end of the ink chamber.
If the needle is not inserted far enough, the ink may do what you described.
Perhaps you need a longer needle.

When refilling a cartridge or a convertor, the air inside needs an escape path. If it's not completely empty, check to make sure there's no ink around the hole. A couple taps on the counter may get the ink to move to the back.

Another solution would be to stand over a sink and push harder on the syringe. You may end up with a few drops of ink on the outside, but most should end up on the inside....

Good luck!
Tom

I'll bet there was some ink around the top I didn't see, because of the way that converter is made. That's a good idea to try tapping it first to see if I can move the ink away. thanks.