Hi Brenda;
I suppose you have noticed you have two grooves on both the treadle's bandwheel & the machine's handwheel. The belt should run in the larger groove on one wheel & the smaller groove on the other wheel. If running from the large groove on the bandwheel to the small groove on the machine you get more speed & can thus sew faster. When running from the small bandwheel groove to the larger on the machine you run slower for either more control or more power for thicker, heavier materials. A very worthwhile setup in my opinion & the sizes are calculated so that the same belt can be swapped from side to side with tension that will work for either, doesn't require another belt.
Miller/TN.
