Random X axis home position

This has been bugging me for awhile now..

Whenever a print is started, the Y axis will go to home, then the X axis will. Occasionally, the X axis will jerk to a sudden stop about 2/3-3/4 of the way to the Home position (without touching the microswitch), then it continues through the typical pre-print start routine.

The problem comes that when the X axis doesn't go all the way to the home switch position, the X carriage max's out against the right side of the machine and causes the motor to skip steps.

It does this about 2 or 3 times every 10-15 prints and is beginning to get annoying..

I have verified the X carriage moves smoothly along the smooth rods, the stepper turns smoothly and the idler bearing spins freely.. I'm at a loss as to what it could be unless there is a internal issue with the stepper motor.