This the problem with these Boxford machines.! They come with different cards and setups, this one is completely different to the one I stripped out. I've got a feeling this one you can break into the top board which as the drives on it, the bottom board is the controller which you just leave in place.
I've also got a feeling the Lanze speed controller can not easily be re-used because it's got it's on interface card which talks to the Boxford controller but I'm not 100% on that.

I suggest you go look on the Boxford forum and look for some wiring diagrams or info on which pins are for the step and direction. Or like I did just pull it all out and fit new drives with a £5 BOB, just some of the cheap TB based drivers are more than good enough for these little machines and you can get them for about £10 each.