Had a look at the washing machine wastepipe,its too stiff because of the plastic covering the wire spring.

So needed to think again....no need for any sort of guard....two small brushes affixed either side of the halfnuts so that as the apron is travelling up and down the leadscrew the brushes are wiping the leadscrew from swarf.
The brushes(if I can find it?) will be a piece of door draft excluder this is like those old vac cleaners with a bristle head on them to flick particles of debri out of the carpet.

This should do it. :whistling:
http://www.reddiseals.com/acatalog/D...luders_lrg.jpg