This one is fairly simple YOUR BOX IS f#*$ED i have had this prob 3 times and now the auto guywont rebuild them 4 me as a new one is very cheapp from sss....if u keep driving w o reverse u end up with itself changing MANUALLY with excess pressure behind each gearchange letting off a chirp at even 30 klms i still have a f#*$ed 1 u can have if u want to frieght it... good 4 drag racing.........