To fix a broken seat recliner lever, first, remove any debris or obstruction in the area of the lever arm. Check to make sure the lever is still attached to its base. If not, reattach it. Then inspect for corrosion of the components and lubricate as needed with a light lubricant. Next, check whether anything needs to be tightened, such as screws and bolts that may have become loose over time. Finally, if all else fails, consider replacing the entire mechanism for a more reliable reclining experience.