1951 John Deere B after finishing a tractor parade and returning to the trailer, I stopped and shifted out of 6th gear and the shifer moved but it was stuck in gear tried several times trying to get the shifter back to where it was supposed to be no luck. so onto the trailer in high gear (spooky but it worked to get home) pulling it off the trailer on flat ground I engaged the clutch and nothing so shifted the lever into the 6th position and it would not go but the 2nd time it did and all gear speeds worked after that, Any ideas is the shiftier ball worn or is it the other things involved ??