Simple example Arduino driven air-core motor

This is just a simple example of driving a small air-core motor with an Arduino. The code that's running on the board is exactly as I found it here: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1271537811 The author describes some pausing issue with it that I don't see on my test run. The motor was purchased from Simco, Ltd: http://www.simcoaftermarket.com/specialty-oem/micro-air-core/ - the part number of the device I'm using is 2022-704. [31Jul15] Important note - the phenomenon described in that Arduino forum post DOES appear when the air core motor is driven at 12v, but NOT when driven at 5v! ... https://www.youtube.com/watch?v=ut9GZJTI3iA