To balance any OTA on a mount in declination, you need to slide the tube in the saddle rings or clamp perpendicular to the direction of the declination axis itself.
Most Schmidt -Cassegrain telescopes (SCTs) are heavy towards the mirror of the tube. Because of that, the tube must be moved towards the mirror end in the clamp of the CGEM mount.
The dovetail rails or bars for the CGEM OTAs have safety screws on either end to prevent runaway slides of the tube from the clamp. They are located approximately an inch in from the end of the orange dovetail bars.
In order to achieve balance in declination, you will probably have to slide the dovetail bar until the end of the bar is flush with the clamp. The mirror end or lower safety screw must be removed in order to do this.
After mounting and balancing the tube in declination, be careful not to orient the tube pointing down, since the lower safety screw prevents sliding in this direction.