Also take a look at the springs — often they’re cut leaving a sharp point contacting the battery that may dig into the cell or scrape across it. If the drop compressed the spring it may be bouncing like a phonograph needle instead of staying in firm contact. Bending the end of the spring so it’s parallel to the surface will give better contact too, as will a dab of conductive (“Nyogel” or “bulb grease”) lubricant .