Fountain Pens

Hello, I'm hoping to find someone that has experience repairing a Sheaffer Snorkel.

I recently inherited a Snorkel from my grandfather who passed away in the '80s. I read up on them a bit, and saw that you could buy repair kits, and got everything I needed to proceed. Well...I didn't read the instructions thoroughly before attempting to take the pen apart, and broke the filler tube insert.

It had slipped out the end of the tube, and I thought it was dried ink, grabbed and pulled, and broke it while pulling it out.

I'm guessing that the purpose of this is to keep ink from dripping out the filler tube while writing, but I'm not sure.

Does anyone know if it's possible to use the pen without a filler tube insert? If not, is it possible to find replacements, or substitute another material to fix?