1983 240D driver floorboard floods periodically. I see the drain hole below it on the outside Rocker/Underbody panel; i tried blowing compressed air through it and sticking piano wire through to no avail. Is this indeed the drain hole? Any other options?

All of the water that drains from the windshield goes through a small drain holes sort of below the hood hinges. These frequently clog and can cause water to flood back into the car.

Did you clean these out?

Chuck