At last after 2 years of trying to get round stars, this is a stack of 47 images unguided. The "seeing" was poor and the wind was a bit gusty so I pulled out about 10% of the images. My Polar setup was really good so I just did a 2 star align and let the scope guide itself.
The problem in the past was a sticky gearbox in the base of the Etx making the stars jump into a line on the final image. I simply tightened the bearings and lubricated the gears before adjusting the gearbox position and it now runs really smoothly.
To check how smooth it was moving I engaged PHD guiding and ran the graph below. I think the scope has been sticky from new as the graph always jumped very erratically before alarming out.
This has shown me that its the quality and smoothness of the mount is very important if round stars are needed.
Lovely image well done!
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