The key stock from the motor shaft came off; It was not the proper size and after the constant vibrations, it slid off and fell into the speed reducer.
The Mechanical Engineering Department’s CLT Dominic Martinez suggested powder coating the key to increase the thickness of the piece.
I used a powder curing oven for the first time.
After two coats of powder I added a few thousandths of an inch to the thickness of the key. The key no longer slides off of the motor shaft. The motor has been reattached to the speed reducer and is reverse acting grate is running back to normal.