Hi,
As our mounts use OnStep system. OnStep will consider NCP as true north in coordinates of GEM mode. So DEC movement near the NCP will be act differently from north of Alt/Az coordinates.
Once mount pointing off the NCP a bit, the direction will be change. Refer to detailed explanations in FAQ of OnStep Wiki, this will not impact normal movement of the mount.
https://onstep.groups.io/g/main/wiki/7118
For mount went back and forward like oscillation, it possibly due to AEB protection triggered, as AEB (Automatic Emergency Brake, for collision protection) default threshold could be too low for larger OTA/load, you can follow the AEB tuning guide to adjust this parameter to higher value to avoid this happened.
WarpAstron Support Team