The motors are from ATI as supplied with the Hadron kit, model is
KL17H247-168-4ACurrent is listed at 1.68A, impedence at 2.8mH.
The mirroring is working OK now I've properly adjusted the current but I'll give them a try in serial mode. The troubleshooting I did yesterday has messed up the neat wiring so I have to redo it anyway.
I now have a problem with the X axis motor. It vibrating no matter what current I set. I had previously tried to remove the pulley (stuck fast) and may have put some strain on the bearings. If I can get the pulley off, I'll use the spare extruder motor as a replacement.
I did a test print (without extruder) and motion was quite smooth if a little slow (apart from the aformentioned X axis motor) Steppers were cool enough to touch after 30 minutes or so.
I'll try the test print again after re=slicing with Cura (Octoprint on a Raspberry Pi)