Originally Posted by
Vridar
I'm intrigued. Using a 29 bobbin, geared low, indicates it's a niche machine. What is its niche - Leather patching such as the 29-4?
I'm intrigued, too... apparently it was just a portable machine. One page I found
http://www.doubleveil.net/zssmp/bell.htm has a Consumer's Reports article on it - very portable (lighter than the Featherweight!), but stitched slowly. There should be a Good Housekeeping report on it somewhere, since it has the GH seal of approval.
A couple other pages:
http://www.singersewinginfo.co.uk/toys/bellmb102/
http://www.sewnuts.com/bell/bell.htm
Oh, and to answer the original question - sorry, Jean, I don't know anything about their tension system. Big tangles on the bottom generally mean the top tension isn't set tight enough - try twiddling the top tension knob to fix? I can't tell if it's numbered, but you would want to try higher numbers if it is, or likely turn clockwise if it isn't.