Replacement Shockmounts and Glue?  

Try these
I believe you can buy the shockmounts from any good Herman Miller distributed stores.
Try:
http://www.hivemodern.comhttp://www.retromodern.comhttp://www.homeofficedesigns.com
or http://www.highbrowfurniture.com

personally i would not was...
personally i would not waste your money on shock mounts for that chair, and that base with the sides is for stacking chairs, and is at the very bottom of the food chain,
If you want something cool get the effiel tower
don't replace the shock mounts, drill them and get screws and rubber washers, and go through the effiel tower base
Then you have something , another wise it is just a junk chair on the side of the road.

Hume modern
Go to the link provided... for glue, use PC7 and mask where you don't want the glue to go. That's the only one that works.
http://www.humemodern.com/parts/parts.html

Hume Modern
Will sell you shockmounts. And if you do want a better base than the stacker you just need to glue the shockmounts onto the second set of impressions on the underside of the chair. They should be 7 3/4" apart (from the center hole) and 4 3/4".
And while your chair may not be a huge boon in terms of money it's still a cool and comfortable chair. Good luck!