jsg Could it be the light from a neighbor's window just below the north star by 10 degrees or so?
If your neighbor's house, trees and lights gets into the frame, you will not likely to plate solve. If it is just indirect light from their lights reflecting off of your current dew shield, or off of your SCT's corrector plate, use a longer dew shield temporarily, or use a cardboard to shield their light, so none of their light can reach your corrector plate.
Next, see if you can change the polar alignment declination away from 90º to avoid the neighbor. You also do not need to start the polar alignment with the counterweight pointed at the ground. As long as the scope can travel the 60 degrees of polar axis movement without your instrumentation hitting anything. I personally always do my polar alignment at 89.5º declination, and starting with the "counterweight" 60 degrees off of vertical (being an RST-135 mount, I don't really have a counterweight shaft; but you get the idea).
Declination angles away from 90º will result in less accuracy of the polar alignment result. But even at declination of 30 degrees from the pole, you can still get within 2 arc minutes of the actual pole. I.e., if your declination is 30º from the pole when doing polar alignement, the error can be over 1 arc minute even when ASIAIR tells you that you have perfect aligment (ASIAIR's polar alignment algorithm has lots of errors they don't tell you about).
So, you just need to keep houses, chimneys, trees braches, and light reflections, outside the frame at the start of the 60º slew and at the end of the 60º slew.
Although I have never tried using the ASIAIR's "All Sky" Polar alignment, you can try that too to avoid your neighbors.
You can also try SharpCap's polar alignment. It may not have the problems that you are seeing with ASIAIR. Or even just use a PoleMaster. INDIGO A1 also has a polar alignment process.
Chen
