Hi Harriscmiv,
Sorry, I opted for a longer focal length guide scope because I had read it was better when imaging with long focal length. I also find the Lodestar X2 a very sensitive and capable guide camera.
I did make sure the mount was balanced and PHD2 was calibrated and running with a very small wave in its graph. Below +/- 1. If the graph gets too big, this can cause larger or egg shaped/oblong stars as the mount is moving around. If you are using PHD2 you could check that.
Sorry I cannot help more. I am still learning AP myself (16 months ). I think the ATIK 4120EX just takes great pictures