http://www.searspartsdirect.com/partsdirect/getSubComp.pd?modelNumber=257798030&productCategoryId=1503810&brandId=0247&modelName=WEED-AND-GRASS-TRIMMER&diagramPageId=00001&componentDescription=DRIVE SHAFT AND HEAD ASSEMBLY&documentId=00049358&backToLink=Return to Sub Components list
copy and paste the above link into your browser window. part #52 is the replacement part for the weedwacker. it costs $8.99. we had the same problem just occur last night.
A. Paliti, July 2009
Replace the entire line head. Not as expensive as you mght think.