I have a muncie m20 in my 56, having 4th gear troubles. before i put it in the car i had it gone thru with new bearings synchros seals etc, basically a total overhaul. I have lined up the shifter following the steps from hurst. In 4th gear when i am not accelerating it pops out of gear. Also if i go to downshift to 3rd and dont need to, like when the red light turns green, and try to put it back in fourth it wont go. Have to shift into third then bring it into 4th. Tranny builder said to pull it out and he would check it but i really dont want to pull it if i dont have to. any thoughts??