@RyanH ,
Sometimes there is small pieces of random magnetic debris that gets stuck in the motor.
First, you could try using compressed air to clear out the motor.
Additionally, It could help to spin the motor up and down using voxl-esc command line tools a few times to clear it out (without prop is best, just for safety). Spinning the motor without prop a bunch of times could get the debris dislodged and actually broken up by the moving motor parts, so that the debris is no longer large enough to cause a problem. Reversing motor spin using voxl-esc test tools can help dislodge the debris (you can commend negative power/rpm).
You can find useful info regarding motor testing here : https://docs.modalai.com/voxl-escs/faq/
Alex