The symptom that exhibits in your video is well known.
A popular "fix" for that symptom is to just install the latest firmware.
That firmware (NOT written by the original A820 developers) simply "dumbed-down" the reel servo responsiveness, so that the symptom you are experiencing would go away.
But the source of the underlying problem was not (and cannot be) fixed by changing firmware.
Also, you don't need to send the machine away for "calibration". You'll instead want to learn to calibrate the machine yourself. It was designed for owner calibration. Read the manual.
