CPS Black (PR57K) is very rigid and brittle. I would not recommend it for a part that will see any significant load. I have been playing with a new tough resin, Molecule Pt. I find that it is very similar to the FormLabs in that it has a much higher elongation before fracture than CPS black. I have found that I need to compensate the model for size on critical features as it tends to oversize due to light bleed.
Are you lifting up for layer separation or rotating the tray?
In either case, since this is a tall, slender part, it may be that the shaft ‘slides’ to one side when it’s pressed into the resin and hasn’t eased it’s way back to center before the next layer is exposed. Each successive layer is then a little further off. When it reaches the last reduced section, the cross section area is smaller and so there is less area to force a ‘hydroplane’ effect, so it starts back closer to center. If this is the case, increasing the wait time before exposure should help.
Try creating a layersetings.csv file and adding a slightly longer wait time with each layer as you get about halfway through.
You can also try slowing down the Z approach to 100ms.