I have one of these snares, and there are a couple of things you can do.
1. get new snares on ebay, etc, which is next to impossible.
2. Make your own snares - you will need a 15" long snares and you have to solder the strings in place of the old one's, there's a good tutorial on this forum somewhere.
3. Replace the throwoff, which ruins the snare.
4 Do what I did - the snares attaches to the throwoff on this drum via thin bolt on either end. remove the bolts, buy a copper or aluminium tube with the diameter larger than the bolt. cut it slightly shorter than the length of the bolt, when it's inside the throwoff (hope this makes sense). Reassemble the throwoff with these tubes on the bolts on either end of the mechanism. Now get a set of modern snare wires, and attach with a wire going through the tube. Works like a charm and you don't have to ruin the drum :)
I can take some pictures if you'd like