The element does not "partially" glow...you only see it that way because air is being drawn thru the heater duct at 480 cfm. It's the same principle as blowing a candle flame. Don't expect the coil to glow bright red all the way down, the heat is being drawn off the coil and transferred to the airflow in the drum.
Check the power cord where it attaches to the dryer for loose connections. If you can OHM your heater terminals to ensure that the element is not grounded to the outer shell, then you have a bad breaker.