I have recently bought an old Mercedes Benz cabrio from 1971.
To my surprise, the light of the handglove box turned out to be a little torch. But over the years it had rusted in place and didnt work anymore. Before going to my local dealership and pay lots of money for a replacement part, I thought I might as well open it and check whats in it. Total simple, robust technic, just 2x VARTA DK150 batteries connected via a 1200 Ohm resistance to the + of the car voltage system.
Hence the problem was quickly found: replace those 2x 38year old batteries should do the job! If you Are interested, I can send you a photo of the opened device once repaired (and functioning).
By: Martijn Moraal