Im having trouble with my starter it is on my 99 F-250 with a 12 valve motor and ZF6 transmission and a starter from a 6. 0 Powerchoke every now and then. Sometimes it will start just fine and then sometime the starter just make a click noise and then nothin. I can sometimes role it a little and jump it just a little but not enough to jump start it and then the starter will work. Any idea what might be wrong with it?