Mine were very loud at startup. After about 10 minutes of clattering they would settle into a loud grind, before finally quieting down to a deafening roar. Inside the lid was full of plastic dust. The new ones are much quieter at startup and normal operation. Interestingly, they are labeled 'Red Sea' as opposed to the generic green Chinese made sticker on the old one, so they are defnitely a different unit. I e-mailed Petware direct and claimed warranty, heard nothing, but replacements turned up at the shop a week later.