In a small pot, boil potato in water for about 10 minutes. Mash potato in water. In a large pot, combine yeast and pancake syrup. Stir melted margarine into potato mixture. Add 1/2 cups flour to yeast mixture. Pour potato mixture into yeast mixture. Mix well. Add rest of flour to make dough. Turn onto lightly floured surface and knead until smooth. Put dough in a lightly oiled large pot. Make sure all of dough is oiled. Cover with towel and let rise 1 hour. Punch down and knead 10 times. Divide into halves, shape into loaves, and place into two loaf pans. Split tops with sharp knife and insert softened margarine and Monterey jack. Bake in cardboard oven at 350 for 20-30 minutes. Bread is done if it sounds hollow when tapped with knuckle.