You don't want to loosen the adjuster lock when the chain is slack (ie cam out), it isn't the end of the world but the tensioner will be snapped to "full tight" by the springs. You can push down on the bottom blade mount at the rear of the barrels to go back "slack" then lock the adjuster again. This is a good idea when replacing the blades - new ones will be thicker, making the chain pretty tight - and hard/impossible to get installed on the cam sprocket - if you don't back off the tensioner.