There are two different kinds of screws in mine, the sprocket shape and then some small philips heads. I have a huge variety of driver bits and after trying dozens, finally found one to fit the sprocket but none of my extensions would fit inside the small deep holes the considerate folks at Shark put the screws inside. It took me hours but I finally removed all screws except the one in the bottom of the deep hole in the middle. I used a drill to enlarge the hole but that ended up destroying the plastic shaft that made the hole. I could not get that screw back in but the rest of them are holding and the vacuum works. But next time I will throw it out and buy a new one, which probably why Shark made it so hard to replace the brush. I printed out a copy of your photo of the bottom and where all the screws are and then taped each screw to its location on the photo, so thanks for that.