Troubleshooting: Needle's won't grab yarn to knit

On Ravelry, someone posted this photo of their machine and asked why it was doing what it's doing:
So, lets try to trouble shoot this.

There's knitting on the machine, so the machine is knitting.

Whenever this happens to me, there's one of two things wrong:

1. The tension is too tight - adjust the tension screw down to loosen up the knitting. By loosening the tension, the weights should bring the loops down to where they're evenly distributed.
   
2. The weight has hit the ground or is hung up somewhere - the fabric behind is not being pulled down uniformly.
   

So - check you weights and loosen your tension.