I have a 1996 DP-70 that is does not automatically shift from first to second. If the selector is in 2 speed mode it will always start in second gear. If the selector is in 1st gear only it will operate only in first. I have changed the high/low solenoid the computer and the pulse generator and nothing made a difference. Serial# 9CP005500. Any help would be great. The fluid level and filters are all good. I wondering if something in the valve body may have a common issue. Thanks