I would just replace the turn signal switches with new ones but if you want repair the old one you can have quite a bit of luck with tuner cleaner. Hard part would be finding the little springs if rusted apart.
What is wrong with the ignition switch. Those are hard to take apart and you can loose a lot of little springs quickly.
Also do you have a tilt wheel or a non-tilt wheel.
Here is how you get to the turn signal switch on a NON-TILT steering wheel:
and what to exspect inside the Turn signal switch:
you can see why it's easier just to replace the whole thing.