Capresso c1500 grinder loud knocking, crunching,...

Question

We've followed the factory manual directions for emptying the hopper, including vacuuming it out, w/o resolution of the knocking, crunching noise when the grinder is engaged. The noise varies with the position of the coarseness dial and is least noticeable at the coarsest setting. Is there something we can do before we spend the time and large amount of money to send it back to capresso to be serviced. Thank you for your time!!