This same thing happen to me. I bought mine on Ebay and the box was all beat up when I got it. It was poor packing. After looking at the Brake Buddy, I noticed the bottom was broken so I took it apart and the compressor broke loose from the bottom where it mounts. I called Brake Buddy and they can't send you the parts "THEY" have to fix it. So I sent it to them and they replaced the bottom and the compressor plus found a couple other things wrong which they repaired. I was lucky when I contacted the seller he refunded me for most of the repairs.. But in answer to your question NO it's not supposed to rattle inside...
