Welcome to Utah! Maybe someday we'll meet up at one of the Euro get togethers. I'm in Pleasant Grove.
Both of my lock cylinders were worn out when I got my 89 325i. After taking the door panel off, there is a 'c' clip that holds each of the lock cylinders against the exterior of the door. Just pop off those clips and the lock comes right out. After that, I took mine to Bilco Lock and Safe and had them rebuild my key, then rebuild the cylinders to the freshly cut key. Putting the new cylinders in was just as easy as taking them out.
This is a pretty easy process, and unless you want to be locking and unlocking your car from the trunk for the rest of the car's life, I'd recommend it. Oh and Graphite works really well for lock lubrication as well.