the vacuum pump isn't still running, and i pulled up the front passenger carpet and disconnected the vacuum lines, and the key still won't turn. if it was just one lock, i would guess that the lock was corroded or dirty, but the fact that its both doors and the trunk perplexes me. I'm fairly certain that the key belongs to the locks, since it does turn a little, and the lock knob, as well as the vacuum actuator in the the trunk lock both move slightly, just not enough to lock or unlock the car. i tried a key from a different benz, which fits right into the lock easily, but will not turn at all. with the central locking, is there something mechanical that can jam in one lock and prevent all the other locks from working?

even in the trunk if i move the vacuum actuator by hand, the entire car locks and unlocks with vacuum, so i know the vacuum system is healthy