. . . a couple of nice ones in there too. As for the original . . . that doesn't look like most of the metal/sheen I've seen on dug Alleys and there's not much else to go on for a positive ID, at least from these pics. And while your description is very good, it doesn't help me much either. It could well be an error, grease on the rollers or something seems reasonable, and it could be dug. That's about all I've got. In other words, I have no clue.
And I have to say, your topic title sure piqued my interest - I would love to see a black Alley Chalky!