Ignition switch problem

The ignition doesn't spring back from "Start" to "On" when you release the key while starting, you have to turn the key back yourself after the vehicle starts.

My questions are:

1. Where is the spring that does this? Is this a lock tumbler problem or is it a problem in the switch?

2. If it's just the switch and not the tumblers and I swap just the switch out with one that I find at a wrecker yard, do I have to do any reprogramming with the security fob?

3. If it is in the switch, is there a way to take it apart and fix it myself rather than replace it with one from a wrecking yard?

Thanks in advance for any responses.