I am very new to ASI cameras, and astrophotography, in general. I recently purchased a ZWO ASI120MM-S camera with a ZWO 30mm f/4 Mini Guide Scope. I was hoping to auto-guide my mount (Star Adventurer) with PHD2; however, when I connect the guide camera to PHD2 I find the images to be extremely grainy with a weird dark circle on the top right (see the attached photo). I tried turning the black front end of the guide scope in both directions, assuming it was a focus problem but was unsuccessful (with my current focus settings, I am able to see the stars in Sharpcap). Also, I see that there are two long screws on the guide-scope - I am not sure what those screws are for.
Any help would be much appreciated.