Nothing is wrong with useing brand controllers.
I havent had a problem like that myself but most of the time when there is an issue with a working stick starting to go bad its because of the switches. It wouldnt be the wiring otherwise you would have noticed something when you first started playing with it, unless the problem is that you left some of the copper on the wire showing and its become corroded over time.
If you have one button that doesnt get used much, thus would have a better switch, move that switch to one of the buttons or directions on the stick that seems to be lagging and see if it gets better. If it does then just order a bunch of new switches from Happ since the switches are cheap.