I figured I'd ask here since it seems frequent tetris players get more use out of their joystick than any other gamer. I know a lot of the top players here use joysticks, and most likely sanwa sticks (JLF or JLW) - i'm talking about you jago, amnesia, colour thief, digital, cyberguile, tepples, etc. I use a Sanwa JLF. Have you ever had to replace, fix, or clean your sanwa stick? I know they sell sanwa joystick lubricant but I just don't know if and when to use it. Basically, my sanwa seems alright, but I don't really know if its performing worse than when it was new.
I've also thought about the same thing since building my stick. I read somewhere about using Vasaline, but that doesn't seem like the best alternative. Although at 29.95 for a 5.3 ounce tube (at least from Lizard Lick Amusements), it would be nice if there were an alternative. It looks like it's a white-lithium, high temp grease from what I can tell.
I'm not sure how to diagnose maintenance need in a Sanwa stick, because I use a Seimitsu stick 99% of the time. I'd say in general though you only need to clean/grease your stick once if it's not providing uniform resistance. It should move smoothly and without sticking. Unless your stick has seen "arcade volume" use, or it's gotten very dusty, or you often have crud on your hands while playing, there shouldn't be a problem.