My 2 yr old Whirlpool has screw in LED bulbs, standard socket. I just put new light boards in a friends 10 yr old Whirlpool, integrated LEDs, flashing light issues. Old 40 appliance incandescents were the industry standard as the appliance bulb has a smaller glass ''footprint'' and was common across many product lines so it took a while to phase them out. I guess like 1157 car bulbs.