Spent most of my morning working on something’s to try to figure out what is going on that would cause that loud of a "grinding or rubbing" noise. From what I can tell from the sound in the video it is as you think, that the black gear is rubbing on the chip. In the below picture check to make sure that the sprocket is installed to where it flat and level in the Slide tray.
In this one make sure that there is no Flashing on it (the small circle had some)
The last thing is just to make sure that Everything is level and installed correctly. This does not solve it completely but it does reduce the overall noise that the loader makes I will continue to see what I can do to take away all rubbing and grinding noises. However you won’t be able to stop the noise for the motor.
One last thing to keep in mind is that with the shells off it will sound quiet but once you add the shells it turns the shells into an amplifier. This will be reduced when you have paint in the loader and you are on the field shooting.
Let me know if any of this is helpful. If nothing else we can have you send it to us and we can look at if for you to see what we can do.