I am having a problem with my 71 Challenger. It has run fine all summer until I went to start it the other day. It started to turn over but never actually started. Since then when I go to start it I can hear the starter relay click but the starter does not turn the engine. I have had the battery and starter checked out at Autozone,they are good. They checked the starter 4 times on the machine, every time it checked out ok. I replaced the starter relay and checked the battery cables,fuses, and grounds,all appear to be good. Lights,radio,electric fan work fine. I do not believe it is the neutral safety switch, ocassionally when the linkage is not in the correct position it will just do nothing, no power goes to the starter relay. I also tried moving the gear lever and starting it in neutral, it still does not start. Any ideas of what else to check?