I have a question concerning the bearing setup on the cnc fusion sx2 z axis. I'm not saying anything is wrong, yet.... but something doesn't seem right to me.

I've been having issues over time with the z axis progressively get worse z depths. so i was cutting plastic last night and notice that the head was moving quite a bit. Figured it was the gibs loosening up, so took the ball screw and mount off to adjust the gibs, and the gibs checked out pretty good. So then i started looking at the bearings and ball screw and looks like the bearings are shot, as the ball screw could wiggle back and forth quite a bit. I could see the inner races move around and realized that the bearings were gone, only had this kit 7 months now and not a ton of use. Not the end of the world, bearings are cheap I can replace them.

Now my question comes to this, since I converted a PM-25MV recently and have read a ton of G0704 builds and all use either double row angular contact bearings or 2 single row angular contact bearings, It seems that the way the bearings are set up on this cnc fusion kit is incorrect, but please correct me if i'm wrong. I'd rather ask the question here and get everyones opinion first.

First of all, the finish on the diameter of the ball screw where the bearing sits has a horrible rippled finish and the diameter is .005 undersize of that of the bearing, this right here alone I feel is wrong,

Second would be that both of the bearings pockets are larger than the OD of the bearing, again, this I feel is not right either

And lastly, the bearings used in this axis are (2) 6000rs deep groove ball bearings spaced out on the outer race and preloaded on the inner races. This is what looks like caused the bearings to die out so quickly. As far as i know, these type of bearings are not supposed to be used in conjunction with each other and preloaded, i believe they are mainly for radial loads and very minimal axail loads, but i'm certainly no expert with bearings so this is why i'm asking the questions here.

My plan is to replace the bearings with a double row angular contact bearing and a thrust bearing on the ballscrew diameter being too small, I think my only option is to shim it, not ideal but the only thing I can think of other than having it laser welded and turned or ground to the correct diameter

please let me know what you think.

Thank you
Kyle