Jeff,
any luck yet? If I remember right, the fan blades are secured to the shafts by small allen set screws. Kinda hard to see, but they should be there.
For replacement I'd try an MB wrecking yard to see if something matches up. If that doesn't work, then I'd call somebody who does a lot of Pagoda restoration work, they might have a blower they're willing to part out.
George Davis
'69 280 SL Euro manual