Seemingly out of nowhere, I cannot turn the key in my 2005 Chevrolet Impala. This happened once a year ago, and I just tried turning it for about 20 minutes until it began easily rotating, and I had never had that problem again. I suspect I have an issue with the ignition lock cylinder. I have tried several keys, and I have tried tapping on the key and the cylinder while turning the key, with my foot on the break. The videos I've seen all show needing to turn the key to remove the lock cylinder.
I've tried the tapping method with a screwdriver and a hammer (softly). I've seen some videos suggest using an air chisel (at low power) to do the tapping for you. I don't have that, so I'm having to do it by hand. How long should I expect to try before deciding that this isn't going to work?
Further, if I can't get the key to turn, how can I remove the lock cylinder? I've seen some videos suggesting a mobile locksmith to "drill it out", but I don't understand what that entails or what that gets me. How much extra do I have to disassemble, and how much extra damage do I have to do, to remove an actually broken ignition lock cylinder if I have one?