Not only this: I purchase a set of fine screw drivers from a local electronics store years ago. Tools where fitting badly into the hands and had almost no grip, highering the chance of scratching/damaging the screw heads. Also they started to rust badly around a year or two after purchase.
Then a friend of mine told me to try iFixIt tools. Purchased the pro toolkit and never looked back: It fits good into the hands, has good grip (never scratched a screw head with it) and looks like new years later.
So +1 from my end for iFixIt tools.
They btw also have good gamepad batteries (ofc. these are cheap china no-names, too, but iFixIt seems to do it's own QA, lowering the chance of getting a bad one + according to reviews they are exchanging them for free even after guarantee time).
Depends on the country you live in I guess? For no shipping you could ask at local mobile phone repair shops, they should have the right tools and experience. At best give them the link to the Wii U teardown guide someone posted earlier.
Else I would suggest looking out for people / service shops experienced with Wii Us, like
https://www.thesunnymachine.com (in case you're in the USA).
take the opportunity to clean everything.
