old and worn out..... Are the rubber bushings on the idler arm hard and cracked???? That poor old light duty steering box is 40 some years old, the grease probably has about zero lubricity left in it, and I doubt has ever been adjusted... Check a Chilton's manual for the proper adjustment procedure.... What is the condition of the rest of the steering linkages, and how badly hardened, cracked, and deteriorated are all the A-Arm bushings????

Just general fatigue is an issue on any old car.... Nothing last forever.....