brought next idea :
Hi you may convert but your recliner chair design will be changed learn here
how to fix recliner chair mechanism
http://www.reclinergenie.com/7-key-t...air-mechanism/

They are a simple enough mechanism, just a reversible motor and many
will use the same mechanism and motor, either mains motors, or 24v
ones. I doubt they lend themselves to conversion to manual use easily.
You would need some means to replace the motors rotation, with a
cranking action using the existing screw thread.