[markgryzwa]

1. Check your wiring to be sure the power and signal ports are oriented correctly.
2. Be sure the code is set up for the proper analog input.
3. Try various analog inputs as we had one with a bad signal channel.
4. Swap out the analog board if you have another one available.

#4 turned out to be the solution for us when we saw similar behavior. Had trouble with the gyro drifting as well implying an analog offset on the board.

Good luck.