Don:

I think, upon reflection, that the pushbutton control unit is all electric, the vac is controlled by the switchover valves (a solenoid that opens or closes a vac line). If they are bad, or worse, a hose has been pulled off, you can have a big vac leak.

You will have to get to them, they are buried (hopefully not as badly as the cluster retaining knob on the W108!) and check to see that they hold vac.

Certainly, if you can hear one hissing and it is no the hose, replace it, it's not worth messing about with them.

I'm still curious as to why the door locks die, though -- are the supply lines clogged? You clould also have a weak vac pump, too, if a leak in the ACC causes the door locks to die.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!