plumbers tape or threadlock glue wrks well.

Ok mate try this stuff it's the best you can get www.henkel-adhesives.com/au/en/about/our-brands/loctite.html?&pageid=19&layout=3
248 Medium Strength Threadlock Stick
if this fails to hold it get a new footstrap screws for starters as it sounds like either the insert or the screw thread is stripped hence not tightening, if the screw and loctite combo doesn't hold then it's the insert mate so try this stuff www.henkel-adhesives.com/au/en/about/our-brands/loctite.html?&pageid=19&layout=3
680 Retaining Compound - Gap Filling it's virtually permanent and the strongest adhesive on the market, if it cannot be removed by tool then it needs applied heat to the screw so remember it's a stayer, as far as moulded thread inserts, I have no idea who if anyone does them??, thats a good question by the way , does anyone replace the board inserts if they pull strip etc
Anyway hope that loctite works mate.

but do spring washers work in the summer........?

Cheers all,

Good advice as per usual,off to buy some of that gear

If the thread is gone then use one of these to build a new thread in the insert

www.powercoil.com.au/

All good bearing supply places will have them

Cheers