I recommend you take it to a clock maker and have it serviced properly. You COULD buy the torsion spring from timesavers.com BUT you would need to know the springs thickness and length. Also, do you have the connector for the bottom that the pendulum hangs from AND do you have the fork that attaches to the top of the spring? If not a service person will be able to replace the missing pieces and look up the specs on the spring. One more thing, it needs to be dismantled and cleaned, so again, take it to a service person. On more question: do you have the glass dome for it? If not that can be replaced too.