Try 32 or 26 mm eyepiece with 3X and see what happened. If it work then you use too high power and that's the problem!

I am not sure that Nagler is 82 degrees might not too well with barlow. I use up to 200 power most of the time! High power reduce the light, object move too fast and easily shaking!

By the way that I am glad that you got a nice 10" dobsonian and do you add some weightat the bottom of your telescope? Because your Tele Vue Nagler with 3x barlow is pretty heavy!