I could barely hear anything even with the volume at 11, sound is very low. Can't tell if it is a worm skip or a bang or the correct sounds.
If everything seems tight with tools used, check for excess end play in the motor too. I.e. grab the flywheel and gently push/pull, maybe twisting slightly to turn, but at the axle your looking for more slide action than usual. The play should be minor; more play = more hop with every pulse of power/change in direction. At the right frequencies youd get more hop and bounce. That might last a half day or forever if thats it.
The forward/reverse differences usually points to endplay or thrusts being off for a can motor. A wrapped hair like fiber at a shaft is another one direction culprit. Brushes and brush dust can mimic it, but you don't have them. A cracked spur gear too..
