I had a thrust bearing failure on my front planetary set that caused of of the gears to wear through the carrier. No big deal, the other 3 gears in the planetary set took up the load. But, as the gear wore through it filled the tranny fluid with metal shavings that eventually plugged the filter. I lost all gears forward and reverse when this happened.



I don't know the 4 speeds well, but I would guess that you are either not getting fluid pressure to any of the pistons that operate the front planetary set or your the clutches for the front planetary are severely worn. Low and reverse are done by the rear planetary in the 3 speed which would explain why you have low and reverse but no other gears.