I assume you of course locked the mount so that the motor drove it. But you did not mention if your setup first balanced the mount?

In doing this, be very ready to catch it if unlocking it starts to drop (to prevent damage), but with the counterweight shaft rotated to be horizontal (counterweight on one side and camera on the other side), if balanced, it should not move when unlocked. If one side tries to drop, it is heavy and not balanced. Adjust the counterweight position so that it does not rotate if unlocked when horizontal. This reduces the load on the motor by equalizing the load. The motor is designed for a balanced load. You can practice this balance at home, but the proof is in the picture.

Experts advise to make it very slightly East Heavy (the East side of horizontal just barely perceptibly heavy) so that the gears stay fully engaged when lifting the east side. This very light load (almost none) reduces "gear chatter", keeping the gear teeth continually engaged. If you swap sides during the night, then this aspect needs attention then.

Zenith does not matter so much, that's just about which way the camera is aimed. What matters is if the motor is having to lift the heavy camera and lens load. A balanced counterweight makes that be little issue if just rotating a balanced load.

I had to buy and add an extra counterweight to balance a Tamron 150-600mm lens on a full frame Nikon. If it is balanced, it performs well.