I have had the back off and there are metal brackets, roughly L-shaped that mount where the bells "should" be. The balls don't really hit the brackets. By all appearances, they are factory original. The cover has cutouts where a round bell would fit perfectly. There is a mounting point--the brackets mount with one screw each. I just need to acquire some king of bells that will fit. I can only guess they wanted the machine to be quiet, as odd as that sounds...