I was cleaning my windshield on my 1995 C280 and slightly lifted up the wiper blade to clean underneath. The wiper works fine, but it now makes quite a grinding noise. I relubed the pistons as suggested in other messages and don't think it's the motor per se. The sound seems to be coming from directly under the area where the pistons are (silver, aluminum housing), but I can't figure out how to get it off to take a look (or know of what's underneath). I don't want to wear out the motor or gearing. Anyone know how to disassemble and remove the blade and piston area? Is this where the gears are located?

remove the small plastic cover at the base of the blade arm by pulling outward on each side, under that you will find a 5-or 6 mm allen bolt holding the arm on.
Remove that bolt and wiggle the arm off.

The larger cover removes the same way.
Sounds like the wiper transmission went night, night.

You have to remove the plastic cowling covers at the base of the windshield at both sides of the wiper assembly to access the bolts that hold down the wiper assy.

It's not a bad job, but is like a puzzle so if you have never done it before, you will have to pay close attention to how it comes apart for reassembly.

One thing to note is with the coverings removed, the windshild will be exposed at the bottom edge and will crack in a heartbeat if bumped by anything blunt.
I always run a couple lengths of duct tape to protect that edge from sharp objects.

Keep searching here, I think there is a link with pictures on how to do this, sorry I did not have a quick link for you.

Thanks for the info. I guess the part is called the wiper pivot assembly (transmission I guess). Can it be opened up and lubricated? It works fine, but it's noisy as hell. I just can't afford to have it crap out on me. The replacement part is about $570 not including installation. My wife will have my head!!