Having problem with the Z axis, started out intermittent. The Z axis stalls or slows down with the stepper motor chattering. When it slows down you hear the stepper motor chatter. When it stops you don't hear anything from the stepper motor. I use the arrow buttons to move the Z axis up and down, intermittently it will slow down or stop in the down movement, some times I can move it up with the arrow button. Sometimes I just wait a little and it works again for a little while. The display shows the Z axis is moving but it's stopped not moving. At first I though it was mechanical perhaps the ball screw but with the Z axis not moving and the numbers moving on the display and the stepper motor being silent I now think it's either the stepper motor, the gecko drive or it not getting the step pulses from the controller. Any thoughts on what parts I should buy first. Yesterday it failed 3 time and I crashed into the part I was cutting then it ran for 6 hours straight without a problem. This morning I did test with the arrow buttons and it failed intermittently more time than I could keep track of, now the machine is down. Please give me your thoughts everyone.

Thanks Joe