Velocity EP finished, but with glitches

Yesterday i finished the electrical work on Velocity EP. I installed a 2S2P 1.2Ah LiPo battery in it. It won't be too powerful but should suit the motor that came with the model. I'll upgrade to brushless later. COG was perfect at first try, although i worried it would be too far back.

But there seems to be a problem: with low throttle all servos and motor are glitching. With zero and full power this disappears. Here's a video about it:



My best guess is a faulty ESC.. but if anyone has any better ideas, please post comments.

I'm not sure if i want to fly the model in this state.. The elevons make quite large movements so it might be risky.