WTD: ITW "Magnetic Valve" keyswitches, low profile variant

Hi, I've just got (another!) AT&T UNIX PC keyboard to replace the one with missing keycaps and -- woe and behold -- this one has a few dead keys! For bonus points, it doesn't use the same switches as the other keyboards: it uses ITW "Magnetic Valve" keyswitches instead -- Details here: http://deskthority.net/wiki/ITW_magnetic_valve Photos here: http://deskthority.net/keyboards-f2/reverse-rubber-dome-switch-t449.html http://park8.wakwak.com/~kaineko2/keyboard/album20110107.html These switches were apparently used in Decision Data, Aydin and Devlin keyboards, and consist of two metal pins and a tiny ferrite in the top of the black keyswitch base, and a pink plastic key which houses a large chunk of ferrite. A small chunk of rubber inside the keycap forms the spring which returns the key to the "not activated" position. The problem I have is that the ferrites on several of the keys have broken in transit... with these being delightfully obscure and apparently obsolete, my chances of repairing this thing (without parts at least) are slim. Does anyone have any of these keyswitches kicking around in a spares box, or a scrap keyboard which uses these keyswitches? Thanks, -- Phil. classiccmp at philpem.me.uk http://www.philpem.me.uk/