Waring Pro 2 spd commercial blender

Blender is one yr old. Motor without container on it sounds fine. When we place the container on it, it sounds noisey; like somethings wrong. the connecting parts don't look worn or chipped.......the blade mechanism appears to be snug within the container....the blade spins freely; ball bearings appear to be ok........not sure what else could be wrong!!??
any ideas??? thanks!