OK this will be sort of long, but if you want to hear that original clock run once again read on. This is the most common problem with a non running clock. First get it out of the dash remember which wire is hot and ground. Hot should be the one with the rubber boot on it. Once it is out turn it over, white cover up to find the three 5mm nuts, one will have a plastic cup around it, break it off. Take all three nuts off, and pull the cover off (be careful not to break it). There are three more 5mm nuts just under where the other three for the cover were. take them off. Pull off the electrical component and turn it to find the copper wraped coil. Look under the coil to find the brass power supply to the coil. It should connect to a metal tab on the far side with a hole in it. If it's corroded that's your problem. Clean the metal and brass pieces where they connect, and solder them back with each other. Clean the contact points on the arm and disk, (looks like a set of points out of a distributor). Put it back together, making sure the arm on the disk is on the teeth of the gear. Should work now. Don't worry about springs going every where they should stay in place.