Honestly the only things to really check for that you can do anything about are the sensor wires being fully seated into the connector and the ESC.
If there is damage to one of the sensor wires internally in the motor or one of the sensors inside the motor itself there is no real way for you to fix this yourself.
You may be able to visually tell if a sensor is broken inside the motor but again even if you can see it broken there is not much you can do ... it would need to be sent in for repair/replacement.
The stickiness of the endplay seems strange ... I would check to make sure that the front endbell is screwed down square and that the rear bearing is sitting flat inside as well.
As far as shimming recommendations go it really depends on the motor... there are always tolerances in these things...some motors have adequate endplay with no shimming...others require 0.020" in shims to get to feel right. It is honestly trial and error with most motors.