The clock has points that touch each other when the spring winds down, which completes the circuit and wind the spring back up. That is the snapping sound that you hear when the clock is running. If you get in there, you have to file the points clean to get them to work again.
I have installed the quartz kit on a friends car. I never did it for my 3 clusters because I disconnect my batteries everytime I put my car away. Working or not, I don't want to adjust the clock everytime that I drive my car