Sounds like your skis are out of alignment. If you have ANY "toe in" it will dart on you. Put a bungie across the tails of the skis (to take out the slack) then measure between the skis about 6-8" in front of the spindle then do the same (at the same distance from the spindle) behind the spindle. Try to measure to a point on the ski that will be straight front to rear like the carbide mounting bolts or something. You want the front measurement to be about 1/4" more than the rear measurement which will give you a slight "toe out". Dead even measurements is best, but I find that a slight toe out gives very good handling on hardpack.
If you really want to align your front end, first get a 5/8" steel rod about 5' long (make sure it is straight). Take your skis off the spindles and feed the rod through the mounting hole. It is a pretty tight fit, but once you are able to slide the rod from one spindle through the other without resistance, you have a perfect alignment. Make sure and do this with the machine weight on the skis (don't raise the front end off the ground) so the caster/camber is correct.