1992 Nissan Sentra Will Not Start

Engine Mechanical problem
1992 Nissan Sentra Front Wheel Drive Automatic 165253 miles

I had to move the gear shift forward or move in while in gear to get it to start. When I turned the key on to start, the dash lights would dim just a little. A month ago I tried to start the car (it started and ran fine the day before) and it would not start neither did the lights dim. I checked the battery and it was ok. I got in it last week to try it and to my surprise it started without any problem. I then tried it four more times and it started ok. On the fifth time, it would not start and the lights did not dim. I thought during the four times that I heard a faint clicking sound but could not be sure. Could this be a relay and if so where would it be located? Thanks!