If you have even some of the spring left you can make a replica.
I used to have to make springs for pocket watch lids when I was making a living as a Jeweler.
You can buy spring wire, all you need is the diameter of the wire and the length.
To make your own spring get the correct wire size and find a piece of round stock that is the same OD as the springs ID.
Cross drill a hole for the spring wire and insert the wire.
Now wrap the wire around the rod keep it tight by holding it tight against a piece of hardwood while spinning it.
I used my Flexshaft to spin it but a dremel or drill will work.
Make the spring longer than you need it to be, i.e. more windings, stretch it to match the original and cut it off.
(just found this site while looking for a wire source: http://home.earthlink.net/~bazillion/matls.html