Make sure your pump nosel is straight with the handle bars (you can adjust on the rear).
If the ski idles straight with handle straight its probably not the linkages. If it at higher rpm pulls to one side, you might have to check your side fins Opas refered too (if there are any) or make sure the pump housing and parts are aligned properly. Your notice an uneven spray behind when driving if there is a clog or broken part. Cheers