I recently picked up a Genco Step Up from 1946. Very cool Art Deco theme, and it’s in great shape. There’s some very minor damage on the backglass because there are 122 bulbs in the back box(!) and no where for all of that heat to go. The bulbs are e10 base (screw in bulbs like an old fashioned flashlight) and aren’t cheap. I decided to go with LEDs (warm white) to keep things cool near the glass. I looked into bulbs from the usual vendors and they were $1 each... which meant that between the backbox and the playfield, I would spend more on bulbs than I did on the game. On Aliexpress, I found some for .30 each. I ordered and waited for them to be delivered from China.
Long story short, the bulbs from China are polarized and won’t work. The ones the vendors sell are not polarized, and would have worked fine.