W140 (S500) Windshield wiper system

[suiteR]

Hi All, I am helping my friend to fix the following problem on his W140 ('95 made).

When switching on the wipers, both wipe one cycle and then park at a rather lower location (almost touching the edge of the windshield) for 1/2 second and then up to another location and park there.

Dealer advise to replace the complete wiper mechanism, very very costly, almost USD 4,000.- for the parts.

We are wondering if we can do anything at home to treat it rather than spending a fortune.

Pls advise. Tks!