Bicycle Mechanics - noob headset questions

I'm removing a headset so I can sell it separately from the fork, but I'm not 100% sure this silver piece pictured is part of the headset and not the fork. Is this correct?

http://i.imgur.com/Y0PwO.jpg

also, I noticed there are four ball bearings missing from the lower retainer. Can these just be replaced with 4 regular ball bearings, or do I have to replace the entire retainer? This is a circa 2005 Campy Record headset. Any suggestion of a good place to buy the right part(s) would be appreciated. Thanks.

Guess: (poor context from that photo)
threadless type, that stays in the fork , but was sold
perhaps by the maker of the bike
when they did their factory assembly,
or it came as part of the headset ,,made to remain in the fork steerer


as to the loose balls , in the retainer, get a fresh set in that size ,
and replace them all ..

I often use just the loose balls packed in a heavy grease
to stick them in place , while I put the fork in.
that way perhaps have room for 1 more ball to spread the load out.

Loose grade 25 balls are cheap by the thousand .

thanks, to clarify, it's a threadless headset, campagnolo record circa 2005. I'm trying to figure out whether I should sell the silver piece that fits into the top of the steerer tube as part of the headset or part of the fork. this is what the headset looks like without that part:

http://i.imgur.com/XXSQQ.jpg

I am wondering if this is a complete headset, or if that silver piece is required as part of the headset.

It looks like an internal wedge insert that takes the place of a star-fangled nut. I had a Colnago fork with a similar insert. They were worried about the sharp edges of the nut cutting into the full carbon steerer tube. So it is not 100% required, but you will need a new star-fangled nut or similar expander wedge insert if you are re-using the headset on another fork.

If you are going to sell it, then the 'silver' part is part of the headset and should be included, good luck in selling it, as it the bearing/ races from the photo look a mess, also, what you have in an integrated headset, they are very frame specific, unlike older external headsets, so have a very small market, selling with the frame it came of would make much more sense.

To me that headset belongs in the discard pile. It has given good service and is ready for retirement.

and the fork will be complained about here , next,
when someone else feels they paid too much for damaged used parts.

bearings like headsets are consumables.

seems like carbon frames and forks are too ..