Front load tub bounces violently in spin cycle

I heard a loud pop when load was in spin cycle and then the tub began bouncing around violently. This is a front load machine…checked out shock absorbers underneath and do not appear to be broken. I have removed top and rear covers…it appears the tub is bouncing inside the shell when on fast spin. Could there be a part inside the shell that is supposed to balance tub and may be broken?