Open the cover at the head of the conveyor. Look at the belt tension as the belt goes around the sprocket.
Tighten the belt tensioning screws at either side of the conveyor head to adjust the belt drive shaft and remove slack from the belt.
Note: Adjust the screws equally to keep the drive shaft perpendicular to belt travel.
While you adjust the belt tensioning screws, push up on the belt with a wrench at the head of the conveyor. Measure the belt slack  at the center of the belt in the lift section of the conveyor. The correct belt slack for Jorgensen conveyors is 0.25" - 0.38" (6 - 10 mm). The correct belt slack for Hennig conveyors is 0.12" - 0.25" (3 - 6 mm). Repeat step 2 as needed.
Apply the jam nut on each tensioning screw to lock it in place.
Install the access cover.