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Set up the system with the OTA facing to the SCP, and the RA counterweight bar pointing directly down.
Looking from directly in front on the mount, a line from the centre of the OTA camera port to the centre of gravity of the camera/focuser unit needs to be exactly parallel with the RA counterweight bar - ie the RA axis.
This gives lateral symmetry about the DE axis. If you have the DE axis balanced longitudinally and the RA axis balanced, then the system should be balanced in all positions.
If you want to rotate the camera for framing (or any other reason) you need a lateral counterweight to bring the lateral balance to the centreline of the mount axes.
Hope this helps. With direct drive mounts getting 'perfect' balance in all positions is critical; with standard mounts it is less so.
Mark
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