Geha Demonstrator

January 27

I have a Geha Demonstrator that I am restoring/servicing. I think (based on resources I've found on this network) that it's a Regent 720. Does anyone have any information on this model.

I assume the nib unit unscrews, but I haven't been able to do that. I haven't used force as I don't want to break anything.

I can remove the piston unit, but the cork seal (head) doesn't come out. It can't pass through the part where there appears to be threads two-thirds of the way between the 2 gold bands (cap band and piston).

Does anyone know how this pen comes apart?

Cheers

ZeroSugar

January 28

It is very risky to open these pens as the clear plastic used for these demonstrators is notoriously brittle and cracks just by looking at it. If the piston mechanism has been removed and the seal is still inside the pen, I assume that the piston shaft is still connected to the seal? Either way, the seal has to pass through the treaded part of the barrel. I would lubricate that part with silicone grease to help the (probably hardened) seal pass through.

January 29

On 1/28/2025 at 9:03 AM, joss said:

It is very risky to open these pens as the clear plastic used for these demonstrators is notoriously brittle and cracks just by looking at it. If the piston mechanism has been removed and the seal is still inside the pen, I assume that the piston shaft is still connected to the seal? Either way, the seal has to pass through the treaded part of the barrel. I would lubricate that part with silicone grease to help the (probably hardened) seal pass through.

I figured out how to remove it. There is a collar threaded in to the threads that are visible. Once the piston mechanism is removed, you turn the shaft to unscrew it, then the shaft collar and seal all come out.

January 30

Interesting. It is strange though that the ring was under the threads in the barrel. Maybe it is supposed to stay in the threaded area of the barrel?

Sunday at 03:22 PM

It's threaded so it locks into place, and it limits how far the piston can retract.

I've never seen a seal like this (I'm used to Pelikans), so I'm not sure if there should be another bit on top, or if what's there needs to be replaced.