It was sort of like an arbor press with a screwdriver built in. You used the press lever to force the screwdriver bit firmly into the screw slot, so it wouldn't cam out, and then turned the bit with another lever.
Do you have a drill press? If so, put the starter in vee blocks (2 parallel pieces of 2X4 screwed to a strong piece of plywood will do), and set it on the drill press table. Find or make a screwdriver bit that is an exact fit for the slot in the screws; smaller won't do. Some socket sets may have suitable bits. Put the screwdriver bit on a shank you can chuck in the drill press, and use the handwheel on the drill press to force the bit into the slot, while turning the bit with a wrench.
Last starter I took apart, the field screws yielded to one of those "hammer on" impact drivers. If you have one of those, try it first.
Posted on Jun 17, 2012, 9:59 PM from IP address 22.214.171.124