On 5/5/2018, Steven Trovato wrote:
"My Magnette brake light switch failed. .... I dissected the switch just to check it out. The switch is probably more than 20 years old. The switch is marked HD89-105 and made in USA. The terminals are split posts with a hole that accepted a bullet connector. The contacts had some black deposits and the disk had some matching black marks".

Same common failure mode due to bad design, slow-make and slow-break contacts get burned due to regular arcing with every cycle, and cheap (bad) contact materials (plain brass). Expect switch life to be defined as mileage or switch cycles, not time. It is common for this type switch to fail around 5000 to 8000 miles.