I took the back of the machine and checked. It does not look like anything is hitting outside and the machine is level. Also the springs on top and the shock absorbers seem to be ok. The outside drum will move freely and the inside drum will turn freely. It sounds like the sound is from inside the drum towards the back. I took the back of the motor off to see if I could see anything that might be hitting. With no luck. Spinning the drum by hand, I could not hear anything.