well finally figured out my tractor , the shifter moves too far in to the reverse position and the synrco keys pop up then the shifter does not want to move back over them . on all the other gear sets there is a gear that stops the shifters from moving to far except going into reverse , so until there is a gear/shaft change this can continue to happen . after taking it apart for the tenth flipping time i decided to remove the synrco keys as the tractor should be stopped before shifting from forward to reverse and it seems to be shifting just fine .