mine wasn't working and then it would work for a second, then not after that. after seeing this thread i opened up the bottom to discover that the gear that moved the feed dogs had some of the cogs broken off, so as to make an incomplete connection to the other gear. i found this site which offers spare parts, but i'm not sure which part it is..
http://www.tandtrepair.com/StylistLine.html
simon
June 2011