Yet another fascinating story. As a kid I was taken by the name 'Crocodile Works', and could never understand how a factory could get a name like that. (I didn't know then that they started there making swords, but that wouldn't solve my problem anyway).
Presumably they would have used water power both to blow a bellows to get a good heat in the furnace, and also to grind the sword blades.
Looking at the few old small scale maps I have, it seems that before about 1860, Aston/Hockley Brook ran in duplicate for most of the way between Hockley and the 'official' Aston Mill, not far from Miller Street tram sheds. The main stream ran to the south, while what appears to have been a mill race with pond ran parallel, a hundred yards or so to the north. When the land was sold for house-building, it seems that the mill stream and associated pond were filled in, and the main brook was culverted from Wellesley Street to Lennox Street. It then ran in the open, under Guildford Street, Porchester Street, Alma Street [and Martindale's factory], Aston High Street, Elkington Street and Lichfield Road, after which it was diverted when Windsor Street gas works were built, to do two right-angle turns before passing under Chester Street and the Birmingham & Fazeley Canal, after which it turned left and flowed parallel with the canal to meet the Tame near Salford Bridge.
Looking at these old documents, I can't help agreeing to what John said a month or two ago, that you can't believe everything that's written down. I think you can go further and not believe the old maps either.
Peter