Just noticed your post is reply 666, so I better reply quick and get past that number.
I think she can be exonerated in this case, the spot on the cord would sit inside the propeller cover, it's also on the inside of the bend the cord has to make to get outside the propeller cover. It could be that the insulation pinched somehow but I'm thinking maybe someone used something sharp to scrape coraline off when cleaning it. This particular 6105 I bought second-hand but I can't even remember who from, it's been a few months. I do remember thinking it was remarkably clean for a second-hand powerhead.