Without switches there wouldn't be scoring and when it comes to disappointments in gameplay, dead switches come as a good second to dead flippers. But what kind of switches we have there, then?

Classic pins used leaf switches with high current contact pads. You would see sparks flying, as they often would drive directly relays that again would drive the score reels. Solid state era pins have them too, but the contacts are tiny and often gold plated.

Microswitches exist to this day and they're the cheap work horse of the switch family. They're small, pretty reliable and technically simple.

Optos appeared in larger quantities in the 90s pins (80s games have some in drop targets). You'll find them on ramps, orbits and other high traffic areas, especially if the passage is wide.

Eddy sensors can detect a passing metal ball and are often in spots where it's not practical to use other switch types, such as in very open areas.