Will a vacuum leak in door lock system impact braking assist pressure on 76 240D??

[240Dork]

Hi folks,

My 240D always loses "boost" assist pressure during braking. Several brake shops have spent hours with the vehicle and still can't find vacuum leak. The brakes, master cylinder, and boost assist system have been checked by three separate shops and everyone is still scratching their heads with no explanation.

Today, as I was picking up axle shafts at an auto parts store, I noticed that two hollow yellow tubes running into the door are severed. I assume these tubes are used to power the master locking system in the car which is currently inoperable.

Could this obvious vacuum leak also impact the performance of my brake assist system? If not, should I replace the master cylinder or other component and forget about identifying the root cause of the problem?

Many Thanks in advance for all your help.

Kind Regards,

The 240Dork