I saw this on ebay and wondered if it would be of any use to FOG members. It apparently takes out the slop where the guide rail meets the MFT. Apologies if it has been mentioned before.
http://www.ebay.co.uk/itm/Tune-your-Festool-MFT-rail-Slop-Stop-/280726327794?pt=LH_DefaultDomain_0&hash=item415c97d1f2
http://www.ebay.co.uk/itm/Tune-your-Festool-MFT-rail-Slop-Stop-/280726327794?pt=LH_DefaultDomain_0&hash=item415c97d1f2