Have you removed the jambs and looked for the manufacturer name? Sometimes glass is marked in a corner, or hardware has a trademark stamp. I don't think you are doomed to replace the windows, the springs (coils?) should be fixable. Most wood window systems use a counter balance spring system concealed behind the jambs. Sometimes the best source of information is the glass repairmen. They have ususally run into about everything that was sold in their area. They are reasonable and will give you an estimate for repair that will be far less than replacement.