The tensioner does not move once the bolts are tight. You snug the bottom bolt and leave the top one a little loose. The sping should put just a light tension on the belt. Tighten both bols up but tighten the bottom one first. Once the top one is done you should be able to twist the belt about 70 deg. The belt going from the crank goinf=g the other way should be tight. The belt will not stretch much at all.