You know, there are times when a "rap" on the starter with a small hammer or something with weight helps at times, but I can't recommend that since it could break if done wrong.
Auto or Man tranny? If you have a man tranny you can pull start or a rocking of the truck in gear will move the starter over the dead spot if there is one. Bear in mind these are all pretty crude methods and by no means the solution. There could be another problem altogether.