Posted for N301ES <lancair@ustek.com>:

 I had an intermittent problem with my Garmin GTX300.  Finally traced the
problem to the connector at the back of the unit.  The unit had been slid in a
little crooked and it pushed the connector foreword, bending the bracket.  A
couple tries later and it plugged in OK but was loose enough to go off and on.
 Once bent back into alignment all has been well.
 
 Robert M. Simon,  ES-P N301ES