If you pick up an old pinball machine, chances are you’ll run into a few bad light sockets. Lights that flicker or simply just don’t come on even after changing the light bulb.
Typically the problem is due to corrosion in the light socket or the light socket becoming loose with age.
The first thing to try is a new bulb. It might just be a flacky bulb or a burnt out bulb.
Next try cleaning the socket. You can try alcohol or Windex on a Q-tip. Or try a bit of sanding with a Dremel tool.
If the socket rotates this means the fiber filter has shrunk with age and the outside (ground) of the socket is not making contact with the base.
The best way to fix this is by cleaning between the base and outside of the socket with a wire brush on a Dremel tool and then soldering the base to the outside. When finished the base will be making solid contact with the outside of the socket and the base. The socket won’t rotate anymore which is a good thing.
You can also run a wire to the nipple at the bottom of the socket. This silver nipple is solder so clean it a bit, add more solder and then run a small wire to the power tab.
Following these steps should fix most socket issues on old pinball machines.