A very common problem with the N64 controller is that its thumbstick wears out and becomes loose. But while some game console repairs or mods can be daunting, this one is something practically anyone can do.
Hand Held Legend replacement thumbstick: https://handheldlegend.com/collections/n64/products/joystick-for-n64-controller-in-the-style-of-joystick-for-gamecube?variant=39266413510790
Disclosure: Hand Held Legend provided the part shown in the video at no cost, but no money changed hands and the opinions expressed here are solely my own. As a policy I do not produce sponsored content.
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Music by Lakey Inspired (https://soundcloud.com/LAKEYINSPIRED).
Intro music by BoxCat Games (https://freemusicarchive.org/music/BoxCat_Games).