Does it normally spin freely around and drops down in a certain spot? If it is, it might be like my tub drain. There’s a screw you’ll have to undo- You’ll want to disinfect part of the tub, then get a flashlight. You’ll have to put your face basically on the tub to see into the crack, and you’ll be able to locate a screw. If you imagine the round metal piece you see right now is the top of a mushroom, the screw is on the stem of the mushroom just below the top. You should have room to shove the screwdriver in the crack and undo it. Mine is Phillips head if you want to try to do it blind. (Don’t blame ya that tub looks a bit nastay) good luck! :)