Nice find! I've always kinda wanted one of these but have always managed to pass them by. A couple have come into Habitat, I think even the blue Pro version. Another thrift store I rarely go to had one for a long time, it may still be there even.
I also saw one on the side of the road awhile ago. I was running late to where I was going and thought to snag it on the way home, but it was gone.
I think the handle marks have something to do with adjusting the handle for different carpet piles, but not sure.
Now you need the attachment kit for it, you know you do. lol