Disabling the speed control on a Thorens TD 125 MKII

I was just trying to demo a Walker Audio Precision Motor Controller on my Thorens TD 125 MKII.  What I found is that the speed control on the Thorens takes over speed control and does not allow the Walker to do it's job.  Does anyone know how to disable the speed control on the Thorens?  I am not sure this is even possible, and am not about to go cutting or splicing wires unless I know it is possible and I know exactly what I am supposed to do.  Thanks.