In a few cases, the stem of the neutral valve needs to be cleaned up with emery cloth. The plunger sticks on the stem causing the transmission to stick.
Pull the valves and lightly emery cloth the stem until the plunger moves freely.
A Way to check the valves before you do anything to them is to swap the forward and reverse neutral valves and see if it makes a difference in the performance of the pedal. If it does, clean up the valve stems as described above.