Hi,
Basically AM or ampilitude modulation is more prone to glithes than thier FM conterparts.Make sure all power wires,eg.any wires, is far away from your antenna wire,motor comm cut and new brushes and also importantly is the caps.And by the way,are you using metal gear servos too?During the servo turns,the movement of the metal gears moving together rubbing each other will create frequency niose also.
Hope this helps.
