Yesterday I wrote up my review of Mad Catz' Street Fighter IV Tournament Edition FightStick. If you're interested in seeing what this controller, and its Sanwa parts, look like on the inside check out this video.
After shooting the video, I did a bit more research and discovered that I was right about the Sanwa microswitches, they do come pre soldered to a PCB. This is to make it easier to switch them out and, I suspect, force people to replace all four at the same time. Easier to do, but in the long run, more expensive.
Update: Yes, you probably should open it from the top, removing six bolts with an allen wrench instead of six screws. Though I didn't have any problem getting into the guts of the controller from the bottom and if you want to switch out the microswitch cluster, I think my way would be faster.