Can anybody out there assist on this problem? I've scanned the archives and it seems that a worn check ball in the valve body of an AW71 can cause a harsh 1-2 shift. This is all I could find, yes mine does have a harsh 1-2 shift but I am primarily concerned with slippage on engagement cold starting out in 1st or reverse, this does not occur after driving it afterwards. A trans man said it sounded like a check valve malfunction could be allowing fluid from the torque converter to drain back into the pan after shutting off the car thus allowing slippage on initial startup, which of course would not be evident after the converter fills up, like I said I found no reference to this phenomenon in the archives.Is there such a check valve? where is it? Or does this sound like something else?