groundFungus:
What happens to the output signal when the power supply voltage is bouncing around?
Servo pwm may not be affected by power supply.
Always good to eliminate things though. Seems he still gets the scope movement with the servos out of the picture.
It's happens even if i don't connect the motor
But even so, the variation on your scope will only account for a 1 degree wobble according to my calculations. If you get a "few" degrees jitter then that might be a power related thing, and I don't think you explained how the servos are powered.