Once again you seem like the guy to ask about identifying joystick parts. Today I received
an ASCII Stick II Turbo for Family Computer with a broken B button. I took it apart and found that the bottom of the switch had popped off and the inner spring + ball were rolling around loose inside. I can't find any part numbers or brands on the switch, but I'm pretty sure it's Seimitsu. I can find very similar-looking switches but not the exact same, so I can't confirm it.
The only markings anywhere are "3-E" on the top and "3-K" inside the base plate that popped off (not normally visible).
It's VERY similar to the ASCII Neo Geo stick on this page which they say has Seimitsu parts. It clearly uses the same buttons:
http://nfgworld.com/mb/thread/580-Neo-Geo-Joystick-Mech
I want to believe it's Seimitsu like they say but, then again, they also say...

THAT clearly isn't the case.
I looked at the internals of other Seimitsu switches and it looks like they have silver-colored balls with conical springs where mine has a copper/gold-colored ball and a cylindrical spring.
I'm sure this is going to be the smallest size available and I can probably get away with using one of the ones I see with blade terminals on the back, but I wanted to get an exact replacement if possible. Of the lists of Seimitsu and Sanwa parts I can find, ALL have blade terminals. I just think it's strange that I can't find this exact switch when it has to be Seimitsu or Sanwa.
It doesn't appear that the switch is easily available from eBay and Amazon unless purchased with a whole button assembly. If I can't buy the exact same button I'd rather buy two so that I can make sure the two buttons feel the same and I don't want to spend too much buying the big button assemblies when all I need is the switch. The specialty websites I see individual switch on all seem like they are either going to gouge me on the part's price or gouge me on shipping.