This doesn't work on simmons. It is a defect in design. What you are feeling is the transfer of the sleds weight and the drag on the carbides change from inside to outside carbides on each ski as the ground changes shape. Because the carbides are a few inches from center, they have leverage on the stearing, when both left carbides have the load, they will force the sled to want to turn left, or atleast give the stearing a yank. Same for the other direction. This effect can only be lessened by a tight front end.. I recomend an ulmer front end bushing kit and go through your plastic shaft bushings and tighten them up as well as any tie rod ends(probably the dog bone one under the rh side panel).
If the skis have worn down, this effect can increase as the end of the carbide which is a pis poor design in the first place becomes more exposed.
Hope this clears a few things up with regaurd to what is going on up front with these skis. They handle great 90% of the time and track straight, corner good but with everything, there is that issue, well, two really, the other being the slow speed effort in corners, which again, is built into it and there is nothing to help it other than hit the gas.