I'm having a problem with my printed jobs. I've noticed it only in cyan and gray ribbons. It starts to make some horrible white lines , and I think there is a problem with ribbon tension, as I've noticed that the ribbon is wrinkling. What's more, this problem is always at the same part of the image, it is nearly always the same size, and it is always in the back part of the ribbon. I've tried changing speed, density and double density, but it doesn't solve anything.
Here there is an image of the problem:

Thanks in advance
