Been there done that! Bought a Kelly green bird chair in about 1967. Works fine if you don't rock much. That's when the machine screws tear the threads at the rubber mounts in the back of the chair. The mounts are a rigid chunk of rubber bonded to a steel plate on each end. The steel plate has a machined thread which cannot take the stress of rocking. We had two children at the time and used it for a rocking chair. Loved the style though.