X-Carve Pausing and Not Moving Smoothly

While doing a v-carve I noticed my X-Carve not moving smoothly. It looked like small jerking motions. You can see the error in the numbers I was engraving on the test stock. I was told that the X-Controllers don’t need pots adjustments so I am not sure what could be the cause. The belts seem to be tight and the v-wheels seem to be adjusted properly. I was told that it could possibly be interference from the spindle so I ran a test with the spindle off and it froze intermittently and still did not move correctly. My X-Carve operated fine until this week so I don’t see what could have changed. Any help would be appreciated. The video seems to large to upload but here is the image of the numbers from the test carve. Its moving worse now than it did during this attempt.

carve2

Entirely within Easel or other software?