By switch not working right do you mean the key hangs up not allowing it to turn each start, or it turns easily but electrical functions are not working correctly?
Screw off chrome bezel from the snout of switch housing which protrudes through the dash. The switch and lock can now be removed from dash as one by pushing its snout back from dash, and pulling it out from behind dash.
Once switch is in hand, you can remove lock cylinder by turning key counter clock ways, depressing a little chrome pin on side of switch housing will allow the cylinder to be pulled out.
You will have to determine if switch is working correctly, and if key is hanging up you have an easily fixed lock problem either replacing it with new (think ‘69 takes later keyway which is more readily available), or repining and cutting fresh key to code by lock smith to freshen the old girl up.
If you are having electrical problems replace switch, and reuse old lock cylinder as is, or have old cylinder repined to freshen up its action to go with new switch.