A consistent left/right shift between alternating engraving lines is commonly visible on vertical edges and fine text. It can come from mechanical play, but even a sound machine can show a speed-dependent delay between the command and effective laser output. Compensation is useful only after the mechanics are known to be stable.
Confirm the pattern
Use a small alignment test with sharp vertical edges and repeat it at two or three engraving speeds. Inspect whether alternate lines consistently extend in opposite directions. Random waves, missed steps or a whole image displaced after one point are different faults. Save the file and all tested speeds so the comparison remains controlled.
Check mechanics before software compensation
Power the machine down according to its manual. Check belt condition and tension, pulley fasteners, carriage play, lens or head retention and anything else the manufacturer includes in motion-system inspection. A software offset must not hide a loose pulley or moving optic. Correct the fault and rerun exactly the same test.
Measure by speed
LightBurn's Scanning Offset Adjustment stores a correction associated with scan speed. Follow the official test procedure and measure the visible difference, not the total line width. Enter corrections only for tested speeds and let LightBurn interpolate between them. Start with a small measured value and repeat the test after each controlled change.