Check all connections by turning the power off and test tightening all screws, that's where I would start. Not only the main power conductors, there might also be some skinny wires going to a terminal strip on the drive, and some of those can be on a 'fault reset' type circuit. Gently pull on the wire at every crimped connection to make sure the crimp is holding good.
First you get good, then you get fast. Then grouchiness sets in.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)