I had problems for a couple years, this summer stripped it down and started at the large pulley on the RH side. Changed the pulley hub (worn where slip clutches insert|), slip clutches, shaker shaft, shaker shaft bearings, shaker cams, cam bearings, pivot pins and bearings, shaker bushings, and arm bolts.
Find the source of the problem, the chaffer rails breaking are just the symptom. And parts are cheaper than downtime.