no crank?

[bmx198706]

i have a 89 nissan 240sx and my problem is weird. lately when i try to start my car. when it is on position i have complete power. i try to turn it over and nothing. first i thought it was the starter. well i went a week and did it again. so i got a new starter again. and went for 2-3 weeks. well its doing it again. so i thought it may have been the battery. the positive end was chewed up. so i replaced battery and also the terminal ends. it started right up. i drove it around for about 2 hrs last night and had no problem starting. i got up for work this morning and had no problem starting. i went to lunch ( started fine and went home to eat) i go back out and no cranking at all again? im getting frustrated on what it might be. any suggestions?

[liquid_cool]

possible ignition switch in the column...or loose plug