The information in this article can help you when the +Control Pad does not respond correctly on Game & Watch: Super Mario Bros.
What to do
Try changing the way you press a direction on the +Control Pad and test whether the issue improves. For example, when needing to move the cursor upward, ensure the entire +Control Pad is not being pressed, but rather press only the ‘up’ button.
Situation not resolved
If the incorrect input continues to occur, despite trying the above information, the device will need to be repaired. Please contact us for support.