i did it. i chiseled out the hard plastic or bakelite socket. then i hit the ball with the grinder. i went to the bearing supply store and bought a sealed cartridge bearing with 1/4" ID. then i went to the hardware store and bought a 1/4" X 1&1/4" cariage bolt, a nylon lock nut, a small bag of brass washers, and a new 1/4" drill bit.

i jammed the sealed cartridge bearing into the hole where the ball socket used to be by putting a strip of old bicycle inner tube around the outer part of the bearing. this holds the bearing in place quite well. then where i had ground down the ball, i drilled a 1/4" hole with a drill press. i then ran the carriage bolt through the bottom, through a washer, through the bearing, through another washer, then through the lock nut. it works like a charm and is super smooth. i just saved about $200.