Pry off the cover over the retaining bolt using the end of a flathead screwdriver. This usually is a small plastic plug on the outside of the lever.
Remove the retaining bolt and set it aside. The type of retaining bolt may vary by manufacturer, with most recliners having a large screw or hex bolt. Use a Philips screwdriver or an Allen wrench as needed.
Pull the lever toward you to remove it from the shaft. If you cannot pull it off by hand, wedge the claw of a hammer between the lever and chair. Apply pressure to the hammer's handle to pry the lever off the shaft.
Slide the replacement lever onto the shaft. Push down on the lever to make sure it is seated firmly and the end of the shaft is flush with the side of the lever. Tighten the retaining bolt and replace the plastic cover.