Hi! MB STARS, 190guy and gillybenztech,
Thanks for your very helpful information. Because of this precious information, I successfully replaced the transmission fluid and filter today.
It took me 2 hours to complete the task and surprisingly there is no leak.
One very important thing I want to share with everybody is that if you notice any transmission problem, you should change fluid and filter first before you start any repairs. The whole kit only costs $22.00.
I got 2 transmission problems before I change the fluid. After the change, both problems went away.
One problem was the hard shifting, the other problem was that I couldn't move the gearshifter from "D" to "P" sometime.
I even got the advice from some transmission experts to rebuild the transmission. That's $2000 at least.
The transmission runs very smoothly now.
Thanks! Have a happy labor day!