Various other relevant links and further reading
Relevant knowledge/discussion which I have drawn upon
https://forums.overclockers.com.au/threads/n64-thumbstick-repair-or-replacement-whats-best.1170136/ (the problem is more complicated than just the gearing. By design the base of the joystick is in constant contact with the spherical bowl it sits in. Unsurprisingly over time plastic joystick rubbing on a plastic bowl eventually creates wear on both the bottom of the joystick and the bowl. I have seemed ppl use a hard curing putty to repair the surface of the bowl by shaping it with a ball bearing and letting it cure but there is little you can do with the bottom of the joystick.)
(like many of you said, the replacements are for 3rd party controllers. I wound up with a couple of those sticks myself. the problem with the 64 is that used a light-shutter wheel design to measure the position of the stick, instead of the more accurate potentiometer that all modern sticks use. another problem with most replacement sticks is that they are mechanically designed exactly the same, so they too will wear out from heavy use. if not wear out faster due to cheaper plastics.
a potentiometer (commonly referred to as a "pot") is a variable resistor. turn it one way, resistance goes up, turn it the other and it goes down. it is the exact same part as a volume knob, only they use two to measure both an x and y axis.
regretfully, the technology is completely incompatible. other replacement sticks you buy on eBay with the 6-wire plug are ALSO designed using pots, however, these come with a small circuit board inside that converts modern pot signals into the older shutter wheel signals. regretfully, cheap products were used, and the modern replacements suffer from some pretty bad input lag/skipping. an example of this skipping can be seen on this video.
that video is also showing the solution. guys way smarter than me programmed an attiny microcontroller themselves that managed to convert the light wheel to a pot signal.
to replace my stick, i bought one of the replacements sticks off eBay, but one of the more modern, GameCube style sticks. these are designed more like modern sticks and will not have the mechanical wear that even normal replacement sticks will suffer from. i then took out the stick’s converter board and soldered in one of the attiny chips i had to program
the result is a controller as good as the original, and a stick on par with a hori mini. additionally, the guys that made the program made it so that if you add an extra wire, you can hold down "B" when you turn the 64 on and get an extra 5% sensitivity.
the USB programmer is only about $15, and chips are $2-3 depending on where you buy them. only a small purchase, but for a stick that will last far longer than an original, and work like it should, there’s no better solution.)
Everything I can find/links I came across on Google and specific search terms
n64 replacement stick after page 10 I got some doge websites; N64 joystick; N64 joystick replacement parts
https://gbatemp.net/threads/n64-replacement-joystick-modules.348011/ stick chat – eBay unknown brand
https://lookanotherblog.com/the-better-n64-joystick-repair/ Kitsch Bent review and how to install
https://www.videogamemuseum.com/2011/05/15/n64-joystick-repair/ - Repair discussion
https://forums.benheck.com/viewtopic.php?f=5&t=35508 rewiring thread pt2
GC replace thread
https://n64today.com/2018/09/22/improved-n64-joystick/ more media on El man
http://www.qwertymodo.com/hardware-projects/n64/n64-controller how data is communicated from n64 controller – big brain stuff
https://spacewalkglass.com/products/new-n64-joystick-for-puffco-peak - Treat for Irie
https://code.google.com/archive/p/n64-joystick-translator/ - The PIC translator board provides a means to swap the original joystick to another joystick of your choice.
Assembly of the controller from scratch is of moderate difficulty, and requires some cutting, soldering, and a PIC programmer.
https://github.com/pothos/arduino-n64-controller-library Arduino N64 Controller Library
http://www.pieter-jan.com/node/10 Reading Nintendo 64 controller with PIC microcontroller
https://kthompson.gitlab.io/2016/07/26/n64-controller-protocol.html N64 Controller Protocol
https://krikzz.com/forum/index.php?topic=7398.0 n64 controller test rom for ever drive
https://www.videogamesage.com/forums/topic/3808-n64-controller-replacement-gear-comparison/ Strangboy and Kitsch-bent comparison
http://tasvideos.org/6051S.html cool write up about doom64 and stick control
https://grabcad.com/library/nintendo-64-shoshinkai-prototype-control-stick-1 A recreation of the Nintendo 64 control stick from the prototype used during the 1995 Shoshinkai Event, at the kiosks that demoed Super Mario 64 and Kirby Bowl 64. The stick has a larger cap, which for some N64 players, could be more comfortable
(Google: N64 joystick replacement parts site:www.reddit.com)
https://www.reddit.com/r/n64/comments/gexgmx/i_made_an_adapter_that_fixes_the_sensitivity_of/?ref=share&ref_source=embed&utm_content=title&utm_medium=post_embed&utm_name=5b83d900b634458da02578ccf40b0649&utm_source=embedly&utm_term=gexgmx - A device that fixes GC to OEM signal input