For anyone who likes this sort of stuff, here's a pic of the remade ATD. Now with re-worked alloy pinion and a new centre shaft made from a bit of 3/4" finish-ground steel stock (ex-lawn-mower rear axle). Self-extractor works by shouldered sleeve 'nut' coming up against a shoulder inside the shaft. It engages after the nut's been undone 2 full turns on the armature. The 'nut' is in fact a 2 piece item, with a head brazed on from the 'outside'. That's the penalty for being too idle to replicate the left-hand thread arrangement. The taper in the end of the shaft is the original one, cut off and turned down, then press-fitted into the new shaft . . . idleness again, as short internal tapers on critical applications can be a pain to get perfect. The outer bit of the ATD itself is also press-fitted over the outboard end of the shaft. Rest of it is the original, and the 'bushing' was pretty OK after a good clean up. No wiggle at all, literally nil, identical overall dimensions, goes on and extracts from an old armature very nicely, retains original dished washer with locating-peg holes and horseshoe retainer under the head of the nut, and cost 35 quid rather than the 144-odd for a new one. Irony is that having gone for manual advance and retard, it'll sit on the shelf until the next time something goes pear-shaped. But just wanted to see whether the conversion and repair was a feasible proposition, which it is, as long as time has no value!
