I'd like to chime in. 
I was over at Ito's house the other day and we did remove the e-clip on the bottom, which didn't really do anything. The joystick did not come apart. I'm thinking that the rust possibly fused the parts together. He has since soaked it (I think) in CLR to remove the rust. Ito, can you confirm?
Anyone have a diagram or schematic out there with how the joystick comes apart? (I've attached something similar to this post as an example).
~ DeLuSioNaL
If he has the balltop off then that's all he needs to do in order to slide the plastic plate and dust washer down over the shaft.
If you removed the E-clip and nothing happened, then it must have some severe rust going on. Normally when you remove the E-clip, the lower spring retainer immediately pushes off the shaft on it's own due to spring pressure being released. At that point the shaft will freely pull out from the base with the upper spring retainer and the spring itself simply falling on the table.
In other words, once the E-clip is removed, it should just fall apart.
If you do get it apart, clean it thoroughly with WD40 or something, especially the pivot bearing and its socket. Spray it with the WD40 or whatever and let it soak and then get in the socket with a toothbrush or pipe cleaner or whatever to get all the gunk out of there. When you have everything cleaned and dry, lubricate the pivot bearing and socket with something light, like machine oil or silicone spray. If you use a heavy grease it will make the joystick movement feel glitchy, and slow to return to center.