The symptoms I had were slippage between 3rd and 4th gear.
If you think you're low on tranny fluid, you can't check it unless, you have the MB tool. If you've had regular maintenance performed, they (stealership) don't check the tranny, unless requested. If your Benz just started doing this, I would have it checked out soon. My tranny went out after 5 days of slippage.
Also, checkout other post on the similar subject matter by performing a search. You would notice that a lot of other owners
with the 722.6 transmission have had similar problems (1997 was the first year with this tranny).