When you open Joystick SEGA SJ-200, it looks very clean... Wires are directly soldered to the pcb. Then 2 other small pcb are plugged to the main board with metal wires and are located at the base of red fire buttons.

The reason why there are no micro swithes or spare buttons, is that SEGA embedded the buttons on pcb, just adding some metal contacts.

These contacts close two signal mechanically by pressing the wide metal plate with stick or buttons. Sometimes these surfaces will get damaged with intense use of the joystick but, it's easy to repair them.

This is the typical electrical circuit for a SEGA Joystick:
 

SEGA SJ-200 PCB