2012 Yaris 2 door's two outer HVAC control rings' lights went out at one time.

Hi my wonderful 2012 2 door hatchback has those three rings to control the air flow direction, fan speed, and heat/cold, left to right. Unusual as it may seem just the outer two rings' nighttime illumination has failed. Has anyone else had this happen? Before I tear into the dash, I wanted to ask you all about it as well as solutions. If it is the bulbs, has anyone used LED bulbs to replace the old bulbs? Thanks in advance!