Apologies for cross posting, but I'd really like to try to get a bit of advice before I start this one.

I just got this pretty pen.

kadett1.jpg

There's clearly a piston problem as the knob just turns with no discernible movement. I'm happy to start dismantling, but would love to have some idea what to expect in there. If anyone knows how the nib/feed is fitted that would be useful too - I'd like to try to get some liquid in there to see if it can't be cleaned up a bit as well.

kadett2.jpg

The 'Rexor' nib is obviously not original (the pen's marked EF and this is a nicely flexible F), but not a brand I've come across before, so any information on that would also be very gratefully received.

Many thanks to anyone who can help.