Geha 790 Piston Unscrews When Filling

[OCArt]

I have a Geha 790 with a tendency to unscrew the piston threads as I turn the filling knob counter-clockwise to lower the piston for filling. Even if I'm careful I can't always determine when the piston has reached the limit of travel to stop turning.

 

Can I apply rosin or some other substance to 'lock' the threads a bit tighter?

 

Thanks in advance,

Dave

[Tweel]

I had the same problem with a Pelikan M101N, and fixed it with Ron Zorn's (rosin-based?) thread sealant. Just a tiny droplet melted on the tip of a toothpick with a heatgun did it. (If you do the same thing, don't hold the heatgun too close to the toothpick or the sealant will blow right off when it melts. )

Edited September 17, 2020 by Tweel

[whych]

Have you tried using a paper clip to tighten the piston outer housing into the body?

Usually this fixes the problem.