Well, it seems the screw behind the blade holder needed to be adjusted. I 
had to find the 'right' spot. If the screw is too tight, you can't move the 
arms to tighten the blade. Too loose and the arms are too loose to tighten 
the blade.
Jason, from TBS, says you shouldn't have to adjust this screw so I hope I 
don't have to often.
Jeanie Wade.....how often have you had to do an adjustment?
Eugene, fortunately it isn't a spring (so far).  I have both cassette and 
jaw clamps on their own adapter for easy change. On this adapter I have had 
to adjust the brass screw for optimal tightening.
David, I hope this helps with your adjustments. Like Jeanie said, use the 
screw driver that came with the machine.

I do like this machine too. The wheel is so light compared to my old 
workhorse Letiz 1212, my second favorite.

Mary Lou