Levellers compensate for modest floor variation and help bring the slate into one plane. They cannot repair a weak frame, a sagging base, or cracked slate; those faults require structural work.
Fit before purchase
Match thread, foot diameter, rated load, and adjustment range to the table model. Each foot should stand vertically on a strong frame member. Avoid “universal” kits that provide no compatibility drawing.
Safe adjustment
Distribute weight across all legs first, then check lengthwise, crosswise, and diagonal levels. Make small paired corrections and measure again after every change. Recheck once cushions and cloth are installed. Lifting a heavy slate without proper support is hazardous, so a table technician is often the safest option.