Automatic transmission

Hi Aluien can get me out of this doubt. Teno a 4x4 2001 Ford escape and 3 months ago the meti sand of a beach and I work very well as if it were firm and a week ago I went back to the same place and no longer advances and makes it very slow and better do not risk for fear that it is stuck, my changes makes me well or the double traction is already spent, I am new in this.

Thas the discs of the box are already spent and skirt, and have to repair the box greetings

Hello, returning to the theme, if they were the discs they would also skate when walking outside the sand in the hawthy