Pretty nifty.
I received the pen early last week, a late model J in blue with a 1550 nib. It was flushed with water a couple days ago and then I started to tinker with it. I pulled out the nib, studied the nib support and it's little channel, inspected the nib, carefully aligned it and stuck it back in the pen. Then discovered that the nib assembly simply screws out. How about that. It sucked water well enough and sort of wrote with it, too. A bottle of Aurora black came today. I blew a few bubbles in the little bottle and wiped off the nib.
Wouldn't you know it but the darn thing writes. As I was warned it's scratchy, and hard to find a position in the hand that produces a good line on the 20# engineering paper I use, but it writes. I like the extra fine line. Hopefully the 9xxx fine & medium nibs I ordered from Brian A. will make it as smooth as my favorite rollerball even if it will never match the heft.
This is going to be an interesting hobby. Hands-on technology and practicality and beauty much like my 1980's 6-series car weakness (the car is blue, too). A Parker 51 vac should be delivered next week. Now I need to order da repair manual, tools and supplies to keep these little gems in proper tune and on the road, so to speak.