Tyler Robert
USA
  
        
          Asked 
  
            — Edited 
  
        
      
    One servo motor for my SIX is practically frozen. It requires too much force to turn it in any direction. When fully assembly, there is no movement and it hums.

It sounds like the servo motor has been damaged. It can be replaced with a complete Lever HDD Servo-motor or by replacing the white bracket on a HDD Servo