As I'm sure you know, these have been MIA for probably 10 or more years from VPI. Mine, on my VPI are still strong from 1996, but maybe your table has gone through more use than mine over the years.
Still, I might not hesitate to call VPI, who knows, maybe they don't have the hinges on hand, but someone found a pair of NOS Hinge Springs laying in a back room.
Sure there's no binding, and are dry? That a little dose of mineral-gun oil with a Q-Tip on the springs and hinge pins might help? Then wipe away any excess.
Otherwise, keep the eyes peeled on places like the bay and such.