In today’s Tianxia stone refiner, the grinding disc is their patented product and can be removed directly by hand.
It is possible that the grinding disc was not assembled properly when disassembling and cleaning it, causing the grinding disc to be uneven, so it cannot be drilled fine. You need to install the rivets of the connecting disc into the small holes on the grinding disc and tighten them. As long as there are no gaps between them.