If the motor is "bad", the chair will not go anywhere at all, and you would be getting a flash code on the joystick control indicating a left or right motor fault.

There are levers for each motor that allows the motors to be placed in neutral to manually roll the chair. Disengage and re-engage both levers to the drive position and now go in a straight line. You probably knocked one of the levers partially out of drive.

There's nothing in the motor case that you can service, beside the bearings on each end, and those would not cause a motor failure that you describe, and you can hear them whining long before they ****-out.

Motor failures are cause by overheating a motor, which in turn, opens up one of the copper wire windings, of which, there's several hundred feet wound around the armature, and then they are all lacquered together. A motor rewind shop would remove this ball of copper wiring, and rewind the motor and replace the brushes and bearings for about $250.00.

You should download an owners manual at Pride Mobility's website. Good luck.