Hello,
I have a terrible experience with servo motors from Aliexprss of the same type (57HBS30 + HBS57), and I wish to share my experience and I hope for any advice from someone here with more experience than I have, it will be much appreciated!
In short, I ordered 3 motors from a seller named "YUN DUAN Industrial Store", I didn't order all together because I wanted to avoid TAX payment. The first motor came fine with no problems, then I ordered again, the second had a problem that made it stall after a few turns (in the future I learned that the disk inside that register the revolution was not close enough to the sensor) the seller send another immediately, and the replacement was ok, then I ordered the third and it didn't work as well! I was perplexed back then because how can I convince the seller that yet again there is a problem? I opened the motor and the disk inside was bent as if the motor was assembled in a hurry, the seller saw the images and send another motor with no problem yet again. So I had 5 motors with 3 that really work. In the summer I had some time and I tried to fix the two and I had success, the bend disk was straightened and both disk were placed closer to the sensors diode and it did the trick. Back then I thought that I got 5 motors for the price of three... BUT!, after a year I finally had my CNC assembled and after a short time I realized that one motor still had a problem - for long runs of code the motor will stall it didn't register the revolution correctly, and after a few uses I had to throw it away. Another motor got burned after a work of ~8 hours (motor defect not too heavy use), and at this stage I decided to order again so I have a backup, the six motor came and had problem with the axes not in center (my guess) It made a weird scratching noise as if the rotor touches the stator. This time the seller was in the belief that I try to con him and I thought the same.. In any way I got partial refund and had to keep it anyway (it does turn just not as it should - I didn't tested it for long runs yet (I was too upset)).
Then the real problem came, I decided to build a second bigger CNC. And I decided to buy this time from a different seller all 3 motors together (it was a little cheaper) since I wanted to finish it faster this time (from "CNC Router Parts Store"). BUT! I got 2 motors that make a strong static noise which I didn't had in any other motor that I got and one didn't turn at all, no matter what I did. This time since I didn't had patient to order one by one I did pay TAX (the equivalent of one motor cost) and at this point I am very frustrated. I cannot keep them a single motor under no load makes noise almost equivalent to my spindle motor! (I use high torque - low speed nema based rotor for hard metal projects and it is very quite (this is not the typical CNC you see out there with 30,000 rpm)). I should mentioned that the motors came with a certificate from March 2011!!! so they are more then 10 years old!!!

Please forgive my long description of the problem, in short, what do I do? can someone recommend a better motor? different supplier? an explanation? I cannot understand what the sellers on Aliexprss gain from all this trouble.
(I should also mention that I work by the book, I never "play" with the assembly, the chances that I am the problem are small, I have decent knowledge in electronics. The power supply I use is 48V 250W for each motor (50W more then needed) which I tested with an oscilloscope before I even used it and my setup is a cheap mach3 breakout board which works with DB25 perfectly. The only reason I didn't resorted to a different brand/type is because I thought it will be convenient if all motors were the same and had the same size and controller, now I think it was a terrible choice)
Thank You Very Much of any advice,
Nir

The video of the motor noise: (please turn the volume up, I rotated the motors to show that they are connected but I am talking about the static noise when they are not turning..)
https://youtu.be/hOodOKadpUU