My '96 e320 is having transmission problems. Reverse is becoming almost non-existant, upshifts are late and tend to s-l-i-d-e into the next gear instead of shifting normally. I also have to feather the throttle in order to avoid slippage through 1st and 2nd gears. The car has 103,000 miles. Is this transmission trashed or does it just need a fluid/filter change? Just for reference, the transmission is model# 722.329