Sabertooth 2x12 RC problem

[buzzy16]

Hi, I have a problem with the sabertooth 2x12 RC that's in my dunp truck, I have the drive motor on he motor 2 on the sabertooth and the motor for the screwdrive is on motor 1, everything works fine apart from the screwdrive only down at a fraction of the speed as going up. I have tried changing the travel and the trim on my controller but it doesn't change anything. I have the motor on the 3 pos switch on my dx8.

I was hoping someone would be able to help me.

thank, you i advance.

buzzy