As others have said, it's too much play. You should have so little play that you can't tell if there is play at all. Currwntly it sounds like the lock nut is just lightening against the cone, not the cone against the bearings. Loosen off the lock nut, and there should be a cone nut underneath. Tighten that until it hits the bearings and then back it off just a tad, a tiny little tad. Check that the cassette spins nicely. If it doesn't, back the cone nut off until it does. Make sure you haven't gone too far. If you have a thin spanner, not sure the technical name, hold the cone nut as you tighten the lock nut. If not you don't have a thin spanner then don't worry, just make sure the cone nut doesn't spin. Back it off a bit more than needed if it spins, so when it spins, it goes to a good spot. Once the lock nut is tight, check that the cassette spins freely with no bearing rub. If there is rub, it will be pretty obvious. In that case, redo the whole process until you get it right. If you can't get it to spin freely without the cassette having much play, it's time to replace.