While I had good luck with RK upgrade to the Deere closing wheel frames, I don’t like a bearing that doesn’t make complete revolutions.  Look at the bearings in a walking tandem, they just rock back and forth.  That being said, I know have a Case 1250 that is needing parallel arm bushings repaired.  I went to the Power Show in Des Moines and came across a both called parallelarmexchange.com. The have jigs for the parallel arms, bore the holes out, install a steel bushing and include the new bushing.