1979 Mercedes 450sl

I just got a new key thinking that the key was worn and it works in everything in the car but the ignition. the old keys started acting like they stick due to not turning in the ignition hole. if i leave the key in after getting it to turn the first time it will always turn unless i take it out? any ideas what to try first.

they steering locks in place.
the gear shift is not locked in place?