My first Parker fountain pen, purchased off eBay about a month ago, was this Parker 21:

Originally sold on eBay as a “Super 21″, when it arrived it turned out to be a normal 21 with a Super 21 cap.
This quickly became my favorite pen (as it has a Fine-Medium nib) and daily writer. I carried it around in my shirt pocket and used it for everything.
Unfortunately, after about a week it started slowly seeping ink into the middle finger of my writing hand. Close examination revealed hairline cracks in the hood (the part of the pen that holds the nib).
I was able to repair the cracks with a minute amount of SuperGlue, and then used shellac to seal the threads of the hood to the section. This worked fine, and the pen stopped leaking.
A few days ago, I was flushing the pen out with water at the sink in my bathroom, when I set it down for a moment. It rolled off the counter, and fell to the floor. When I picked it up I saw what I expected – worse cracks near the clutch ring on the hood.
More superglue and shellac were ineffective this time.

At this point, I’ve retired the pen to storage. I’d like to replace the hood, but the one source on the Internet that has (green and red) Parker 21 hoods has not yet replied to my email inquiry. Sending it off to a “pen doctor” would cost more than I paid for it in the first place.
Sure, I could just go buy another 21 on eBay – but this pen was my first Parker, has a GREAT nib, and it’s just a sentimental thing.
I won a bid for what was supposedly a Parker 51 on eBay last week, but when the pen arrived it was an *actual* Super 21 – a 21 with a 51-style nib, and the same cap that my dark-blue 21 has. However, it has issues – it was stored nib-down for a long time, and all the ink dribbled out, flooded the cap, and stained the hood. What ink was left in the pen has dried in the collector. I’ve flushed, filled, and soaked it in water twice so far, and it’s still not flowing to my satisfaction.
So, right now, my count of “Working Parker fountain pens” is “one”, it being a Parker 51 Special currently filled with Baystate Blue ink.
Update: Since this entry was written, I’ve picked up two more Parker 51 Specials off eBay, and will be putting the Parker 21s into my parts box. Unfortunately, they’re just not worth the cost to fix.