Hi..
I'm actually posting this for a friend of mine, as my 76 450SL has a different locking system. He is having troubles with the central locking system. At present, the only way he can lock/unlock his car is to use the trunk lock. Both the driver and passenger side locks will not turn (I'm assuming it is a lock cylinder problem...both worn out).

In addition, when the vacuum pump kicks on it remains on for close to a full minute. So...if you are in the car, push down on the driver's lock...you cannot unlock any door for one minute...when the pump kicks off...the doors can unlock.

My theory is that my mechanically inclined friend did not realize that the pump was doing this...in an effort to unlock/lock too quickly...he messed up both lock cylinders.

So..need advice about the pump...what would cause it to keep running for so long? After I knock out that issue, we can see what is up with the cylinders...but I bet we need to swap those out.
Thanks!