[Shiraz (Ray)]

Crikey Lee, you are having big problems.

Your original graph showed that the RA is not correcting properly - it gets into a no-mans-land where phd2 is generating lots of correction signals but the mount is not responding. Provided phd is generating normal corrections signals and your mount autoguide speed is set at 0.5x, that still suggests backlash to me (ie the motor is moving, but the gearing is not transferring that motion immediately to the wheel). If you cannot feel any worm slop, it could be due to the internal transfer gears. As others have said and you have tried, you should be able to manage this by offsetting the weights to make it east or west heavy, but the offset weight must be sufficient that it overcomes stiction (ie the mount moves freely under gravity when the clutch is released). If that doesn't help, there is not much left mechanically, apart from bearing preload. If the bearings are too tight, you could get jerky motion - I recently improved my DEC tracking by backing off the bearing preload a bit.

If you are looking low down east, you will be viewing through lots of turbulent atmosphere. The turbulence could have an RA-worse component due to slowly rising plumes of warm air (they don't move sideways, so have less effect on DEC). Maybe do a test up near the zenith and see what happens when you are looking through less air. Imaging below 45 degrees will be a lost cause most of the time anyway due to turbulence, unless your system is heavily undersampled.