1993 Chrysler Le Baron Instrument Cluster Lights

Interior problem
1993 Chrysler Le Baron

I have a 1993 Chrysler Le Baron. I was turning on my head lights while my wife was turning on the heater and my cluster lights failed to turn on. They had functioned fine up until this point and I have not been able to get them to turn on since. My headlights and overhead light work fine, but driving at night and not being able to see my speedometer or any other instruments makes things very difficult. I've checked and replaced almost all of the fuses, so I know they are not the problem. Where else should I be looking and doing?