on my 1995 318i, I can only turn the driver's door key lock clock-wise, so
the doors will lock fine. However, I cannot turn the driver's door key lock
counter clock-wise, to unlock the doors. The key will only go as far as the
"vertical" position. Luckily, the passenger door lock works fine, and I can
enter the car, and unlock the driver's door from inside. I don't want to
come to the situation where I cannot unlock the door at all, so I will drive
my car, but I won't lock it.
Is this a case of replacing the lock cylinder? If so, can the cylinder be
keyed to my existing key?

thanks