Abstract: A seat arm adjustment mechanism has a stop block attached to the back of a seat, and a shaft slidably mounted in a housing on the arm bears against the stop block. A locking arm is slidably mounted on the shaft within a slot in the housing. A spring, disposed in the housing and positionally held by a screw, effects a biasing force against a face of the locking arm. A raised portion of the locking arm bears against a face of the housing. A second spring mounted on a screw between an end of the shaft and a bracket moves the shaft toward the stop block. An elongated rod is slidably mounted on the arm to bear against a face on the locking arm opposite the first spring. Pushing the rod against locking arm allows the locking arm to slide along the shaft, while the arm is being moved to a new selected position. The arm may be raised and lowered, whereupon it stops at the last selected position.