If there was a wiring issue in the steering column all of the lights would be working or not working at the same time. There could be an issue with the wiring in the steering wheel or the light in each switch. The first step would be to remove the steering wheel air bag and have a look at the switch wiring behind it and remove the switches and look at their wiring connections. If all looks OK I would replace only one switch and see what happens. If the new switch works OK all the time then you could go head and replace the other switches. If the new switch acts up like the old ones them further diagnoses would be required, and perhaps replacing the switch wire harness behind the airbag.