Tractor Repair: ford 8n tranny, ford 8n, ball detent

Question
My 1947 ford 8n pops out of reverse all the time also 1st gear pops out when comeing down a hill

Answer
it sounds like the selector shaft is cracked.it could also be the ball detent spring for the selector shaft is broke as I've never seen one of these tractors unfortunately i cant tell you where the detent spring is or the procedure for removing the selector shaft if it is broke
if you can take off the gear stick plate do so and you should be able to see if the shaft is broken