This might help-

It is from a "How to repair a mono-wiper"

Tools needed for repairing the wiper arm

-Small mirror
-Dental pick or small Allen wrench

Instructions:

-Raise the hood for improved access.

-With the ignition off, rotate the wiper switch to the first position.
-Turn the ignition on and off rapidly, so as to move the wiper arm out of the park position.

-Move the arm manually to the straight up position.

-Remove the three-sided rectangular cover (lower end of arm) that extends over the cap by pulling it straight up from the bottom end.

-Using a sensitive fingertip or a dental mirror, locate the two small recessed rectangular openings on the underside of the cap at roughly the 5 and 7 o'clock positions.

-Using a tool with a 90 deg end such as a dental pick or a small Allen wrench, release the catches in the access holes while pulling the cap upward with the left hand.

-Now that the entire articulated wiper actuator is in plain view, you will see as I did that the shaft that extends the arm up into the windshield corners (twice per sweep) is very likely no longer lubricated.

-Remove all the old grease from the shaft and bushing using for example a cloth soaked with lacquer thinner or similar, moving the arm back and forth to expose the arm surfaces inside the bushing.

-Apply new lubricant and I don't mean WD-40. I used Sil-Glyde, a silicone grease which has a working temp range of -20 to +400 deg F.

-Reassemble in reverse order.

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Haasman

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'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)