Meisterstuck 642 cork replacement - help

[Restoration_Iceland]

 

I've got a Meisterstuck 642 with a broken cork seal on my restoration table. I saw somewhere that people have replaced these seals with silicone o-rings. Any idea what size seals to use for this or where one can find appropriate cork replacement seals? For reference the diameter of the piston looks like its about 5mm and the nut that holds it is about 8.5 mm so I would expect the seal to be about 9mm. All advice is welcomed.

[lobster]

I measured a couple of nuts at 7.7mm and the ID of the barrel at 7.9mm.

Two o-rings ID 3/16" (4.7625mm) OD 5/16" (7.9375mm) made a good seal with a little silicone grease.

[eckiethump]

I use "O" rings for piston fill pens, but NEVER on a vintage celluloid pen, particularly Montblanc, always cork.

et

[lobster]

6 hours ago, eckiethump said:

I use "O" rings for piston fill pens, but NEVER on a vintage celluloid pen, particularly Montblanc, always cork.

et

 

I could probably use o-rings in cheaper pens (even celluloid), but in a $1000 Montblanc I use cork too. (Actually, in all Montblancs that came with cork).