Tony,
Yes, stepper was size 23. The turret spindle was mounted in two ball bearings with the toolholder plate bolted onto a flange. Worm wheel ratio was 30:1.
Your picture shows an additional microswitch, presumably to generate a position signal for tool number 1.
On the Yahoo Mach group John Stevenson suggested using a rotary table with the ratchet mounted behind a toolplate. I though that it might be possible to use this idea,
but mount it directly to a stepper. The ratchet would take all the downward forces on the cutting tool and the side forces are very low on these little lathes. One of the Chinese 250 microstep drivers would give enough resolution with enough torque at low speed say, 12 rpm. Just an idea for discussion.
Ian