One has a Knox K35 medium and the other a Knox K35 fine. I have two Konrads now, and neither have the original flex nibs. Consequently, I wanted to transform them into more regular sorts of pens. Ostensibly my pens are for pedestrian activities like mathematics, and while it is fun enough to make an ornate integral sign, it isn't actually useful to do so. The flex nib is interesting, but I didn't care all that much for it. My first Konrad would sometimes drop an ink blob. I'm working under the assumption that the section gap is the only culprit. I pulled the nib/feed out and checked for the air tightness of the barrel by trying to blow through it and by seeing if it will hold water when the feed is out and the section is pointing down. No matter how I positioned the nib/feed there was always a gap running all the way around. There is light pouring out around between the nib/feed and the walls of the section. So I pull the piston out and run a light down the barrel looking at the feed. Back together (the section doesn't really provide a very secure grip on the feed in my opinion) Guess what? Gusher. Pulled the nib/feed for inspection and gave the feed a good cleaning.
Put a bit more silicone on to replace what was lost fiddling with it. I unscrewed the piston mechanism to check the seals, lubricant, etc.
Filled it up.hard starter.wrote three words.ink gushed out. I gave it the standard rinse with ammonia and water. I just received a Noodler's Konrad in Roaring 20's Tortoise.