Jittery servos

Hi,
I am trying to use the SSC32 with my new AL5A arm.
after completing the assembly, I first tried connecting just one servo to the ssc and send it direction command via Arduino.
The servo basically moves, but keeps shaking.
I am using the included power supply, first with the power share jumper on and later off, no change.
I’ve tried controlling other servos - again, one at a time, but they all behave the same
To test the servos, I’ve connected them to the Arduino directly and they behave just fine, even when powered from the Arduino’s power supply.
What could be the problem? Could I have gotten a defected board?

Thanks,
Zvika

Can you post a few images of how you have the SSC-32 set up? A video of the issue would be ideal of possible.
The servos will vibrate to a certain extent when they are subjected to a load (they have to constantly be powered to stay in place).