The gear for the headstock quill is 10 teeth, 1 Mod, so a standard metric gear. Usually gears below 12 teeth are adjusted to prevent undercutting the teeth, but for this job they are not. I got some suitable gears from a Chinese supplier, but never got around to using them as my SL went abroad. However I might make up a handle as I have a spare headstock that I might convert into a small pillar drill.
So the gear spec is 10 teeth, 1 Mod, OD 12 mm. I think I got mine from Ebay, item number 166358248864 (in the UK).
