I just spoke to a local Mercedes mechanic (non-dealership shop) about rebuilding the center-vent vacuum-controlled actuator in my 260E. This is a common issue in the W124-bodied cars.
The way most people get to this involves completely removing the dashboard, etc, etc.
His way of doing this is different:
Cut open the plastic heater box! He says he has done this many times and simply glues it shut.
Anyone ever heard of this or done it? What a colossal cost-saver!
Interested in replies!