without seeing the other end, if it is a ball, maybe you can cut ball off with dremel tool, remove cable, replace spring, slide cable back thru conduit, then "birdcage wire slightly", then clean wire with brake cleaner and make a mold with wood that you could melt lead into and pour into mold? crude but a possibility? in my line of work we re- end cables using this technique, but were using 1" cable, 40,000 #pull, works well.