Recently bought a 6420 with 24 speed Powerquad and electric reverser. Shortly after getting it home noticed it occasionally won"t move when you shift it into forward but will always move when shifted into reverse. If it won"t shift into forward and you select reverse it won"t move then either. Shut it off and restart and then it will move. Seems to act up whether clutch is used or not. I have a general idea how the system works but I don"t have a Tech Manual (yet). Would anybody be able to give me a general idea of the workings of the reverser system and all the switches, solenoids, modules that are involved?