The 2 large bolts on the top and bottom of the housing heed to be loosend, then the 2 smaller adj. screws need to adj. for the chain tension, then re tighten the larger nuts as well as the nuts on the adj. bolts. If you need more slack that has to be done by hand, rolling the housing forward to let the tension of. Lay on the floor, look directly next to the bottom large bolt, should see the slot.