[Shiraz (Ray)]

I can't see much difference between the two sets of images?

In any case, the distortion could be either optical or guiding.

Check if it is optical by taking a short (eg 1 second) exposure of a few bright stars and see how it looks - if the distortion is still there it's optical and you will need to re-align the scope and camera.

If the phd graph is smooth at that focal length and pixel size, you could possibly have set the guide exposure too long to correct for short term jitter. again, suggest that you find a bright star and try guiding on it with 1 second guide exposures - that will at least tell you how much short term tracking error there is.

Since it guides differently when east, suggest that you also try increasing the weight bias in RA - these mounts need a slight bit of imbalance in both RA and DEC to work properly.

as a general comment, that scope/camera is a fairly bulky load for the mount - it should be possible to get it to guide OK, but it will be very sensitive to how you set it up. You don't have to open the mount to adjust the worm backlash - it can be done easily with the mount in one piece.