After killing the rebels over and over for ever, I tried the lower level ones on the south side of the zone and the newb valley near the druid ring. Got this to drop from "a runaway clockwork". Of note, it was the only one I killed that was wielding a weapon and on the offhand, something that looked like a torch and it was smoking...assuming it was this.
my newbi tank Tuffynuff, killed 8 clockwords near druid ring and got 3 to drop in an hour today, but killed several while they were still blue and not one dropped. so, as usual, it is the luck of the drop.