The car is a '94 E320 wagon, when put into reverse, the car won't move. I rev the engine a little and after 2-3 revs it catches and backs up normally. The fluid is at the correct level and all appears to be fine in forward gears, shifting is normal. This is my wifes car and she just brought it to my attention tonight. Any ideas? the car has 104K miles on it.

Thanks.