To dig with a slip scoop the dirt must be fairly loose. If it isn’t they used a hook shaped ripper to loosen it first. Your lines must be around your back under one arm only, not around your waist, because if that scoop trips unexpectedly (and it will) you want to be able to get out of its way. Ideally your lines should be just long enough that when starting out between handles you can stop horses by leaning back and to control speed. You don’t want to be leaning too far forward, it’s like a walking plow, you must be comfortable, it’s hard enough work without making it harder.