Help with Chinese 1605

So a couple years back I bought a zaxis assembly from China that has a 350mm 1605 balls crew assembly. Well it locked up the other day from sawdust buildup, I didn't realize when I took it apart that the bearings would fall out and I've lost some. I got online and ordered a 1605 3 circuit 5 lead nut from vxb bearings and when I got it in its quite a bit to big and has a lot of slop. But it has the same 1605 number. I measured the outside diameter of the screw and got 15.3 is that right. Or does anyone know where I can get the correct replacement nut.

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