Topic: gamecube controller thumbstick repair

Hi Guys

i have a gamecube controller (an original one) that i bought online a few months back and it has been working fine since however earlier today it seemed to develop a fault. it seems to register backward movement without me tilting the stick backward. the severity seems to change but it is practically unusable, how can i explore tallon 4 if samus keeps walking backward? how can i save hyrule if link just runs toward the screen? i know its a problem with the controller and not the gamecube because i have tried my other controller and that works fine (i do need both of them working for 2 player games).
i should probably specify, the stick is not getting stuck in any particular position, neither is it difficult to move around at all, its just that im fighting against a backward current anytime i move with it.
i suspect i will need to open it up and clean it, i have seen people use those cotton tip things in between the elastics on the square thing that attaches the thumbstick to the circuit-board.
before i do that however, i thought i would come here for any advice you guys might have, anything i should know before opening up the controller would be helpful.

here are a few specific questions i should ask:

what size tri-wing screwdriver should i use for the screws?

should i use rubbing alcohol or is it best to avoid getting any liquid on the circuit-board?

are there any other things that might be causing this and if so what can i do about it?

thanks for any help you can give me on this.

Honestly just skip.opening it up and buy yourself a new GC controller. Aren't that much nowadays anyway.