If you watch the video, I explain it but basically don't over tighten the set screw on the vertical risers for the servo mount. If you do it right you can get it at a 90 degree angle when it's fastened.

2 x 3mm washers needed behind servos to bring into proper alignment. This pictures shows the wrong adjustment on the servo mount. See the angle between the plate and the mount.

mount is nice and level.

The top hole is sized correct to tap 3mm threads which makes lining everything up much easier. nut and bolt was used on bottom hole.