Leveling the Neptune 4 Pro works best as a sequence: mechanical plane, probe mesh, then printed Z offset. Repeating only the last step cannot correct a loose corner.
Heat the bed to the temperature used for the test material if the current Elegoo manual calls for a heated routine. Let it stabilize, then home the printer. Use the auxiliary leveling screen to move the nozzle to each wheel position. Adjust the wheels in small passes until the reference gap feels consistent, circling the bed more than once.
Run automatic leveling after the wheel adjustment and save the mesh. Large differences between neighboring points deserve a physical inspection: plate debris, a trapped magnetic sheet, a loose wheel or gantry misalignment. Do not hide a severe slope with a dense mesh.
Print a single-layer pattern across the useful bed area. Tune Z offset while watching fresh lines. Round strands that do not meet need slightly more squish. A translucent, scratched or ridged surface needs more gap. Make one small change, then judge several new lines.
If the center looks good but one corner does not, return to the wheels and regenerate the mesh. If the whole pattern changes together, Z offset is the right control.
Check that the printer actually saved the result before powering off. Use the current Neptune 4 Pro interface guide because menu placement can change with firmware.
The mechanical-then-probe-then-offset order used here mirrors the general bed leveling approach that applies across most FDM printers, not just this one. If assembly or wheel tension is still in question, the Neptune 4 Pro setup guide covers how the bed hardware should be installed before this routine begins.