Singer thread tension upper thread tension complete
 for Singer sewing machines such as:
 Singer 237,239,240,241,242,247,248,250,251,252,258,259,288,
 Singer 300, 360, 362, 367, 368
 Singer 400,403,
 Singer 500,502,507,509,513,522,527,533,543,
 Singer 600,603,604,620,625,626,628,
 629,630,635,638,640,645,646,649,
 Singer 1247,1263,1280,1288,
 Singer 1802,1803,1812,1852,1862,1872,
 Singer 2404,2430,
 Singer 3101,3102,3103,3105,
 Singer 4825,4828,4830,
 Singer 6102,6104,6105,6106,6110,6120,6130,
 6136,6146,6152,6156,6174,6184,
 Singer 6201,6202,6211,6212,6214,6215,6217,
 Singer 6606
 Singer 7100 series
 Singer 8500 series
 Singer 8600 series