Neither here nor there at this point, but the likely reason it was an intermittent problem was probably an "open" in the armature. It's kind of like playing roulette, If the armature stops rotating in just the right spot it won't spin the next time you hit the key. You could have probably wacked the starter with a hammer which would jog the armature just enough so it would start.
Had to do that on a couple vehicles a bunch of years ago.
