1 more start problem 97 150. Solenoid?

bought the truck used a week ago with 177 thousand miles and never had a problem with it starting. Now just today I drove it for 2 minutes, parked it for 5, and when I came out it wouldn't turn over, I could hear the relay under the dash click twice but the starter never clicked. So I had to get to class and when I came back I tried again, same thing but I noticed the gauge on the dash said the batter was giving good voltage, everything else worked fine, radios lights etc. So I cleaned the batter terminals, checked all my fuses, still nothing. Then I knew that solenoids go bad once in a while and the small wire on it you can just pull off the post I started cleaning that (it was a little corroded) and I accidentally contacted both terminals and it cranked over. So I turned the key on and held both terminals, the truck started up fine, I released the connection and it ran great. would this be the solenoid? the corroded wire? or a bad relay? I'll go and clean the wire as much as I can but it's so small I can't fit a wire brush or anything in the female end. Hopefully I found the problem but I don't know which one it is!

Thanks!
Dan

EDIT: HA!! I went out 6 hours later, never cleaned that wire, and it started right up with the key. :sly:

oh and by the way, I FINALLY hit 100 POSTS!!!!!!

Congrats on both.