"Cranks when in on position and nothing in start position".(?) Sounds like the starter might be stuck in the ring gear. Remove the starter motor and inspect the bendix gear travel. Make it extend by hand. If it travels out too far then the snap ring on the end of the armature shaft is out of place or missing. This can make it stick in the ring gear making it crank when you turn the key to "on". Then inspect the ring gear all around for bad, rough teeth. HTH