When troubleshooting your vacuum system you must know where the hoses and lines go
What's wrong with my Mercedes?
Look for the cause in the drive mechanism
#1 Failure Point are the rubber diaphragms in the door lock actuators
Pump mechanisms breaking apart and piston bolt failures
Repair kits and parts are not available new for the twin diaphragm pumps
Double check for damage and use a product to scare them away