Clip cord sparking? Well let's first rule out that there isn't a break in the cord or solder connects, although usually that will result in power interruption and the machine will just cut out. It's been my experience that a sparking clip cord happens when the clip cord hits the frame and grounds out the connection.
Most of our Pulse frames have been designed to prevent this so I had to fish out an old brass frame to illustrate the problem (I know brass is a non ferrous metal and won't throw sparks). When the clip cord end swings in, you can see where the bare metal clip hits the frame. This will result in a power interrupt, a skip or an actual arc (spark).
This is an easy fix. A small piece of shrink tube or electrical tape on the exposed clip cord connector should insulate the end from the frame and eliminate your problem.
If the problem persists you need to work backward from the machine to the electrical panel. I always swap out each piece in the chain of electrical delivery to try to discover my problem. Process of elimination, but always remember safety first.