The definitive answer from the manufacturer is YES, "clackity/clack" IS a normal sound for the DREAM Machine........which is good to know because I really like mine.
"The clickity noise is actually some backlash designed into the driving gears on the end of the rollers (spacing between the gear teeth). It is normally slightly louder in the wider settings and very quiet in the thinnest setting. It is very normal and should not be a concern. As you have noticed, when you adjust the clay thickness, the roller not connected to the motor moves back and forth. As the roller moves away from the other roller, the gap between the gears increases and causes the clicking noise. Again, really nothing to be worried about.
3. The clicking also varies with the speed. Using the hand crank, you tend to go fast and slow. The clicking will also speed up or slow down. The motor turns at a consistent rate so the clicking is consistent. Again, very normal and nothing to be worried about."
Anita in AZ