When installing any track you should have the nut on the tension spring backed off all the way. Once the track is installed you need to move forward and stop without using the brake. Then go in reverse and again coat to a stop without using the brake. This wiil neutral out the slack in the track. Now you place a wieghted string across the track and then have someone stand on the track while you check sag. I think the sag should be 1/2" to 3/4". Remember, you have new tracks so they will be tight. You may not have to adjust them right now. Don's were tight from the get go but has since been adjusted. Track tension should be checked often as you don't want to ruin a good track or throw one. Hope this helps.
Steve A.