MY K2f points taper had been got at by some previous urchin and the 'key' area on the taper was butchered. Couldn't find a decent replacement so bought a new one. Came yesterday - and doesn't fit. Wouldn't seat in the armature, so I carefully filed the 'key' as it was quite proud and the keyway is only a few thou deep. Still didn't fit. I eventually discovered the taper didn't match the armature by some margin, so set about repairing my old one, something I had been trying to avoid.
I stripped it down & clocked it up in the small lathe. Turned off the old taper & bored the plate hole 10mm (I used an endmill, as a drill was likely to wander). Then turned up a new taper from bronze (it's aprox 9 deg on the compound-slide), leaving a register on the back to locate in the plate. Bored it 7mm and cut off. Then silver-soldered it to the plate (didn't think soft solder would be strong enough) and re-assembled. Yet to decide whether I'll make a punch and jig to create a new 'key' or whether I'll fit a small pin instead. Then I'll do the same with the new unit so at least it's functional.