I have been posting off and on my observations looking at the ASCOM driver setup seeing that when the rotator is idle the indicated voltage will drop from ~12.5 to ~5V. Several other users on this forum have reported similar things and lots of esoteric ideas have floated about. In order for the dome to even function I've set the rotator low voltage to 0.5V.. Tonight I finally got around to replacing the provided "LY1205" 12V 5A power supply with a 12V 5A Mean Well power supply I got from Jameco. ~$29 US. First off the Mean well supply is the same physical size but weighs about 3 times more. Also, the 12V leads have wires which are shielded and at least 4xs heavier.
Bottom line is that with a proper power supply the driver indicated rotator voltage sits steady at 12.45V and never wavers. Another Nexdome user had "sendserial" errors which were in fact caused by a combination of this sorry to be blunt cheap power supply and bad solder joints.
I think the only reason I've had pretty solid performance is I use a high quality 12V powered USB hub. I hope my rant here helps some other person.. The only difficult thing is the center pin of the dome rotator 12V input is rather fat. The Mean well I bought has std 2.1mm pin and I had to cut the leads and replace.