I thought you would know i2i lol , well while the site was down I managed to track down a data sheet and now these proximity switches are operational with a nice little relay board, I think they were used as home switches in the original design as they only operate at one end of each axis only, I understand this is not the best way to go as the repeatability is not good, so im going to get the drill out at sometime and drill the recesses at the other end of the axises and use them as limit switches.
Ive still not got out and completed fitting the tacho yet, although Ive got all the bits as i had to take a break and goto work, yuk! yuk! yuk!.

Rick