I'm not really down with Sanwa's sloppy sticks, I much prefer Seimitsu's tight action, especially in their older sticks. I have a few very old mechs, similar or identical to the NeoGeo joystick (but in this case I think it was ripped from some other device). Its super-tight action, small throw, square gate and stiffness really work for me. So I wanted to use it, and I had a few of these Hori Saturn sticks kicking around:
The mech inside it was, if not actually a Sanwa device, certainly similar in performance. It was the same nameless white-based arcade style stick you find in all kinds of controllers. And so it had to go. It was attached from the inside, so I didn't have to remove the top plate. Four screws and out.
This left a square area, and four posts. The incoming mech was square with some extra bits, so I removed the four posts and cut two notches using a Dremel tool:
The fit couldn't have been better. The new stick base was almost exactly the right size, and with the wings in their slots there was no movement at all.
The only thing to do next was secure it in position, and for this I went an unusual route:
That block of wood holds the mechanism against the base of the joystick quite nicely. The double-sided sticky pad is only attached to the wood block, the foam provides just enough clamping action to prevent it from moving without being stick to the base as well. All told the whole mod probably took 45 minutes, including a lot of staring and thinking.
These sticks are super easy to work on, and I could have maintained Saturn compatibility easily, but I wanted to use my NeoGeo-style DB15 pinout since I had a stack of adaptors already made up. So I desoldered and yanked the huge PCB, wired up the buttons, and presto! It worked first try. (Which is cool 'cause I sometimes get the stick orientation wrong).