This Upper Thread Tension Take Up Check Spring (Part #66774) is a reliable replacement.

Fits Singer models: 101, 1200, 1200-1, 1247, 1263, 1280, 1288, 1802, 1803, 1812, 1852, 1853, 1862, 1872, 1873, 201, 221, 222, 223, 237, 239, 240Srs., 2404, 2430, 247AP, 250Srs, 2712, 2718, 2722, 2724, 2730, 2732, 288, 301, 3101, 3102, 3103, 3105, 327, 328, 329, 337, 338, 347, 348, 353, 354, 360, 362, 366, 367, 401, 403, 404, 413k, 416k, 417, 418, 4522, 4525, 4526, 4528, 4530, 4538, 457, 466, 476, 477, 478, 4825, 4828, 4830, 500, 502, 503, 507, 509, 513, 514, 518, 522, 527, 533, 534, 538, 560, 600, 6011, 6012, 6021, 603, 604, 6102, 6104, 6105, 6106, 6110, 6120, 6130, 6136, 6146, 6152, 6156, 6174, 6184, 620, 625, 626, 628, 629, 6201, 6202, 620E31, 6211, 6212, 6214, 6215, 6217, 6221, 630E, 630E31, 635, 636, 638, 639, 640E, 645, 646, 648, 649, 6513, 6548, 6606, 7015, 7021, 7025, 7101, 7102, 7104, 7105, 7106, 7108, 7110, 7136, 7174, 8002, 8007, 8019, 8100, 8200, 8500, 8600, 8774, 9500, 9600, 9900, 

Also works with many of the Kenmore 158 series machines.