It is kind of hard to tell unless it is shot. On my 603 I was getting the chatter so I just replaced the shock. Later I find that the opposing spring can break at the hook which if it goes you will be to peeling wound strips of your belt out from behind the harmonic balancer, possibly wreck the front main seal, and also in my case the belt ripped through the trans cooling lines at the radiator. Ugly! The damage cost me much more than the spring. "Would have-should have-could have" Just not thinking.