Wendell Bragg

UPDATE - Sickle Bar Shakedown

Looks like a previous owner tried to repair the bracket.  Notice the poor welding job.  On the bottom, the weld prevented a proper mounting.  Also notice that one of the bolt holes is wobbled (egg shaped). 

The hinge had problems of its own.  Notice the peened mounting surface and wobbled bolt hole. 

I think all of these factors contributed to an unstable assembly and resulted in the violent shaking.

But while surfing for something else, I stumbled on a NOS  Bracket and a used hinge that appeared in very good condition so I jumped at both of them.  I am now reassembling and will let y'all know how it works out.