Finding the backlash on my new SX2 benchtop mill to be frustrating, I added a pair of thrust bearings to the bearing blocks to let me tighten the handle without stiffening the movement too much. Probably overkill but I also added a standard bearing as well. Feel free to adapt/improve my design but I thought it’s share the measurements I ended up with.
The parts list (per axis) is 1 x SMR148ZZ bearing, 2 x F8-16M thrust bearings, and a custom spacer you’ll need to find/make. The lead screw for each axis has an undercut at the end which is just the right size for the bearing race to drop into. To avoid this, I machined a 3mm thick spacer/washer to take up that space. I made mine 16mm in diameter with an 8mm hole to match the bearing race, but this isn’t critical.
Here’s a drawing & part list for the modification. note I’m just a hobby machinist and a new one at that. As such I make no warranty that I know what I’m doing. Your mileage may vary: SX2 Modified bearing block adding thrust bearings