The cause is not the motor unit of the Technics and the turntable is excellent value for money so not worth changing unless you are upgrading to something better - which will cost.
One thing to check is to see whether you get noise when you move the tonearm across the platter manually - with the amplifier set at your normal listening volume. I have come across situations where you can get grounding issues as the tonearm wiring twists as the arm moves across the arc of it's travel.
It's a rare enough occurrence but worth checking, along with the other checks suggested above.