Post#2 » Tue Jan 04, 2022 1:16 pm
I've had this same issue with many controllers for various consoles/handhelds. Most likely the rubber button membranes just need to be cleaned so that they make better contact with the pads on the board.
I've fixed it by taking apart the controller, taking out the rubber membrane underneath the offending button/D pad, and putting it onto a piece of paper. Push down on the membrane "button", and then gently move it a couple inches across the paper 2 or 3 times. It should leave a black streak on the paper from the black graphite pad. Repeat for all 4 "buttons" on the D Pad membrane.
It also wouldn't hurt to use a Q Tip and isopropyl alcohol to clean the pads on the PCB where the membranes sit.