Fan occasionally jumps in speed or rotates when it should be facing straight

[johnscerri]

As an endurance test I ran set a boat up on the floor inside and gave it a path to follow. Gains were set at 1,0,0. The fan turned on, rotated to try to reach its target and stayed in that position. The fan would periodically (every 10-15 min?) jump to a much higher speed for a second or so then return to the limits set by the gains, potentially damaging the motor. It would also occasional rotate to a new direction and back again even though neither it nor the path had changed.