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squares:

A quick way to check whether a square is "square" is take a piece of material with a straight side, put the square against it, and draw a line, then turn the square over and draw on top...

Try arc-euro as they have some spares.
http://www.arceurotrade.co.uk/Catalogue/Machine-Spares/X2-Mini-Mill-Spares
Although not many now
Peter

I stripped my X3 down, and i think i still have the screws and nuts still.
Im not sure if they are the same, but if they are you can have the bits.