Lounge chair restoration project  

Maybe it's because no one
has any experience with that particular mechanism, dano.
It's not clear to me from your explanation or photos exactly where the wobble is occuring. Is it where the post connects to the tilt/swivel, or where it threads into the base? Does there seem to be a part missing or broken, or has it simply worn out? Perhaps rather than try to restore the mechanism, it might be better to retrofit a newer different one as has already been suggested.

Thanks tktoo!
The wobble is caused by the second of two slightly visable (silver) wear marks, one near the top, the second right above the threads. Its at that point where the post contacts the "springbox". I definately am ok with a new mechanism, just insanely confused given three difft. suggestions from what seem to be good sources. I assumed after skimming some of the posts that this would be an easy answer from the likes of spanky or lucifersum, but I may be wrong...could my chair be so common that most would wait for a version without a wobble? If I put in one to two hundred to make it whole again, sure seems worth it to me. Thanks again!

From what Abacus seems to...
From what Abacus seems to say on their Plycraft page, many different types of swivels were used by Plycraft, and Abacus has no direct replacement that duplicates the originals. And, their style 402 and 502 swivels require modification to be installed, since they are not direct replacement parts. Unless you can source an oem replacement swivel or post, it is likely there will have to be some kind of compromise you will have to make in order to fix the wobble.
http://www.swivel-chair-parts.com/Eames.html

From what I can see, it seems like
the holes in the stamped sheet metal parts of the springbox must be worn to the point that they have become oversized. The taper at the top of the post, I think, was designed to accomodate some degree of this, but time and forces have had their way.
It's possible that a talented local metal shop/welder could repair the springbox either by "swaging" the holes or welding on new plates with properly-sized holes, though it might be less expensive to simply replace the entire mechanism with a similar, possibly better, modern design.

I don't have any easy answer.
I've reupholstered five of these so far and I think at least four of them have been different designs. (And at least three of them have cracked plywood around the seat mechanisms, so you might have that to look forward to, too. Good luck!)

from the few..
that iv'e owned the threaded shaft is welded to the base part and there is a nylon sleeve that enters into the base hole. Maybe yours is missing the sleeve and weld has come undone?

Dano, the more I've thought about it,
and I'm going to stop now, it seems like there must be at least one part missing. Nobody in their right mind would design metal-to-metal bearing sufaces like that without providing a means to lubricate them. Like setag mentioned, could be a plastic sleeve or bushing.

Thanks for all the help!
I am still surprised this hasnt come up and been solved already...I have dealt with the cracked plywood on my first one. there are replacement mechanisms available, its just there is confusion on which one will work best. I will share the results when the project is done.
It has been bizarre trying to nail down all the varieties of knockoffs that have been made over the years, difft. bases, mechanisms etc. Does anyone know when either plycraft or selig stopped making their versions? And is it true that there are thousands and thousands out there, that they are not rare at all...?

the mechanism shown is also...
the mechanism shown is also on my first chair, intact and working, and as far as I can tell there are no missing parts... of all the checking i have done, the other mechanisms I have seen have a round tension knob that protrudes downward. The simple spring box on both of mine seems less common. Maybe newer? Thanks again for the help!

Are you asking if Selig...
Are you asking if Selig and/or Plycraft knockoffs of Eames lounges are rare? No, they are not. There are indeed thousands and thousands of them out there. Possibly millions, and half of them show up on Apartment Therapy sooner or later.

Same Issue
I just recently found a Selig chair that looks the same. The chair Mech is very lose and I'm thinking there is a plastic part missing as the hole the pole slides through is just way b igger. Where can I find that part. It seems all I need is a plastic brushing to have it not wobble around. My Mech is two springs compressed like some Mid-century office chairs that are height adjustable. Also where can I find screws for the shell and arm rest and I'm missing one stay on the bottom....There are plenty of Eames parts out there but not one for a plycraft or Selig.
Thanks! S

I'd probably start by
trying sites like McMaster-Carr and searching for sleeve bushings that might fit.

I had one of those chairs and I know
the part you're talking about. I believe it's nylon, not plastic. Try the link below--I didn't see that specific part listed but they might be able to help if you email or call directly.
This place also has some parts but that bushing isn't mentioned---still, I'd try contacting them: http://www.modernconscience.com/store/page231.html
.
http://swivel-chair-parts.com/EamesPlycraftAvailablepart.html

I think
You are looking for a "hub liner". Spanky sent you the site. It is on the page I linked below. I was missing one for a plycraft chair a few years ago and none of the ones they have available worked for me but it was not the "eames" style plycraft chair so you may have better luck. Without the hub liner the chair will wobble, sometimes tremendously. need to get an accurate measurement of the inner diameter of the female part exiting the base and an accurate measurement of the diameter of the male part that exits the bottom of the chair etc. you can call them, they are pretty good over the phone as long as you make sure you are not just talking to the receptionist.
http://swivel-chair-parts.com/HubLinerPage.html