On my 1994 E420, the problem was with the pumps which sit at the bottom of the washer fluid container. The pumps sit inside rubber gaskets which deteriorate with age. You might want to just replace the gaskets first, but in my case, the pumps were very old and brittle, so I ended up replacing it all. I think the pumps are about $15 each, while the gaskets are less than $1. The tricky part with my car was connecting the hoses to the pumps, since the hoses were also very hard and dried out. Just try to be patient and you should get there.