I had reason to remove my kitchen worktops and a couple of base units this weekend and since it provided easy access to the otherwise difficult to reach magnaclean pro I decided to remove it and give it a good clean. I was surprised to find no sludge at all but when I tested the magnetism with various ferrous items it has no magnetism at all which has baffled me. I'm wondering if it could have been defective from installation about 10 years ago. Is anyone able to shed any light on this?