This tool will make it easier to level your X Axis rail.

Attach both left and right pieces onto the X Axis rail on the left and right side, lower rail and slide feed into lower rail grooves, this'll stabilize the X Axis Rail for alignment.

Then loosen the Inner left and right POM Bearings and outer bearings. Tighten the outer POM Bearings, turn and adjust the inner bearings till they are set and level.

Once leveled, Raise the Z Axis just enough to remove Tools, Then level/tram your bed.

UPDATE:

This will work on X rails that are 20mm x 20mm and Lower base rails that are 40mm x 40mm.

NOTE:

Loosen belt before adding this to the rail, will make it easy to install and remove, can always retighten belt when finished calibrating.

Also, when installing, slide it on with the corner and tilt to push on, it will make it easier to install and remove.

When removing, raise rail to get bottom of "Jig" out of lower rail grooves, then twist left or right then pull, will come right off.