If the tumbler isn't working properly, one of two things is happening. Either the key is worn out (try a different one) or the lock cylinder tumbler is going bad. In that case, you will need to replace the lock assembly.
The only real tricky part is if the key has a sensor which the car has to recognize to start. If it does, you may want to have a shop or locksmith replace and reset the system. It will require some specialized tooling.
Here are the directions for replacement. The attached pictures correlate with the directions.
2004 Saturn L Series L4-2.2L VIN F
Ignition Lock Cylinder
Vehicle Steering and Suspension Steering Steering Column Service and Repair Removal and Replacement Ignition Lock Cylinder
IGNITION LOCK CYLINDER
Ignition Lock Cylinder Replacement
Caution: Refer to Battery Disconnect Caution in Service Precautions.
1. Disconnect the negative battery cable.
2. Remove the lock cylinder bezel from the steering column shroud by carefully prying with a thin-bladed screwdriver.
3. Remove the steering column upper trim panel.
4. Remove wiper/washer switch.
5. Insert the key into the lock cylinder and rotate to START position.
Important: While rotating the cylinder back to the START position, depress the locking button on the top of the ignition module with a thin pick-type tool.
6. Slide the lock cylinder from ignition lock cylinder case.
Important: The actuator blade within the ignition module housing must be in the RUN position to install the lock cylinder assembly. If rotated, replace it to the RUN position using needle nose pliers.
1. Insert the key into the ignition lock cylinder and install it into the ignition lock cylinder case.
2. Install the wiper/washer switch.
3. Install the steering column upper trim cover.
4. Reconnect the negative battery cable.
Let me know if this helps or if you have other questions.
Images (Click to enlarge)
Wednesday, November 6th, 2019 AT 7:44 PM