Sometimes the bearings wear inside the motor and give a bit of wiggle in the can creating noise and vibration and could end up damaging the motor. Replace these bearings and get the motor back towards being new again. If you are replacing for two motors then you need two packs of these bearings.
These bearings were sourced from a high grade industrial supplier and are great quality. The bearing codes are (2 x 6800-ZZ 1 x 6900-ZZ).
Wondering how to take the motors apart? Check out Pavel's video below about 5:30mins into the video he takes the motor apart. Be very careful when splitting the can as the magnets are super strong always attach the motor to a larger plate to help and keep fingers out of the gaps.