bballfreak

My central door locking totally stopped working, so I examined the vacuum pump under the seat, seems to whirring when I turn the driver, passenger and trunk door lock with the key. So, I unplugged, the tube that is going to the pump, which is connected to three vacuum lines, 2 going to the front, and 1 going to the trunk. With all these vacuum lines connected, I pulled vacuum on tube that was disconnected from the pump and it holds vacuum.
So, I assume that there is no vacuum leaks anywhere.
This is a funny looking rubber connector, one port going to vacuum pump which then splits 2 going to the front and 1 going to the trunk.
I also removed the driver side door panel and vacuum line is super tight. I also checked the resistance as stated in MB technical repair book and that is OK. So, all three door actuators cannot fail at the same time.
The tube going to the vacuum pump, seems to be a bit lose, so ordered a new one. Electrically, all looks ok, it seems.
Any suggestions? BTW, is there a vacuum reservoir? I think it is on the driver side behind the fender wall? but that has nothing to do with central locking? right?
Please MB gurus help me