Wiper Link Retainers

Repeating failure of wiper linkage connections might be due to restrictions in the pivot post assemblies. The cast housing has only a short bronze bushing at each end. The void between the bushings will fill with rusty crud. Eventually the portion of the shaft inside the bushings rusts too. Bushing wear, shafts wear. Pivot become nearly impossible to turn.
Properly restored wipers can run smooth and quietly, even on a dry glass.
It is a heck of a lot of work to do though.
Good luck