A chair adjustment mechanism has a pin retaining member (as, for example, a sleeve) with a slot having two laterally spaced pin receptors. Each receptor is partially defined by a peripheral wall of the slot and is further defined by a spring finger that projects along side of the peripheral wall. With this arrangement, a pin may be received through the slot and into a longitudinal slot of a second member (as, for example, a J-bar), which longitudinal slot defines a rack. The pin receptors may be positioned such that with the pin in a first of the pin receptors, it is engaged by the rack. In consequence, the pin retaining member may be moved upwardly with respect to the second member by notching the pin over teeth of the rack against the urging of the spring finger. The top of the longitudinal slot may have a cam surface to cam the pin into the second pin receptor such that the pin is now spaced from the rack. This releases the pin retaining member to be lowered with respect to the second member. The longitudinal slot may have a second cam surface proximate its bottom end to again cam the pin into the rack.