This photo is of the underside of a La-z-boy recliner, and shows a rotating square bar (attached to the handle on the side of the chair) with a cam that has a couple locking positions as shown. A pin rides along the outside of the cam, with springs that pull it into the resting position but can be overcome by a reasonable amount of intentional force (moving the wooden handle to rotate the bar) to change the position of the foot-rest. The photo shows one end of the pin (the other side looks the same/symmetric) and the photo shows the pin in the "out" position where the setting can be changed.
This chair gets stuck in the "foot rest out" position, and no amount of force applied to the handle can get the pin to spring out so that this can rotate (the wooden handle would break first). When I put my fingers in to manually move the pin it seems to extend the springs etc as designed, easily. When the chair is tipped over on its side, it also works. When the chair is right side up or upside down, it does not work. Stuck in the open position, it's impossible for a limited-mobility person to get out of the chair without help (and then the chair must be laid on its side to get the foot rest back in).
I think the problem may be related to the wear on the metal as shown in the slight deformations around the locking position, that may create a deeper cavity or stronger lock than what may have been an original slight slope allowing the pin to roll out of the lock positions.
Is there a fix for this?