Our flat has been playing Resident Evil 4 on the Wii together (well, one flatmate plays and we all watch and ‘advise’). Said flatmate dropped the nunchuck on the ground mid game and somehow broke the motion sensor in the remote. This resulted in the character constantly swiping their knife, making the game unplayable (you couldn’t even move). After a quick google search I came across a forum thread where someone had also broken their remote, and one person suggested tapping it quite hard on the back. This fixed mine, and after playing Wii Sports for a bit I can safely say it is fully functioning. That saved me $100, so I thought I would post it here on the off chance that it helps someone else out.
Just in case anyone was wondering if I ran into problems with this later, the controller is still fine.