Here's how I set the tension. Mitsu has a "special tool" for this as well that fits on a 1/4" ratchet and has two pins that insert into the tensioner bearing. I found a pair of needle nose pliers work fine for the job and I was able to get more than enough torque on the bearing to set the tension. Once tension is set the Pin can be removed and engine rotated two full rotations re-check all 5 timing marks for alighnment (4 cams and crankshaft) and also check the tensioner. you should still be able to freely insert the pin or (allen wrench) into the tensioner. If you cant insert the pin refer to your manual for min/max clearance between tensioner and pivoting tensioner bracket if its within spec your good to go, if not re-set tension and try again.