How long have you had your current machine? I think your tension problem is not the machine itself. Have cleaned out the lint recently...lint is a four letter word to sewists and can cause many problems. Clean all you can,and the do it again! Sounds like you need to adjust your tension.....top only..the bobbin tension is adjusted at factory and really should not be fooled with....check your top tension and if you are getting eyelashes....your threading is incorrect.it takes a bit of patience and a lot of perseverance, but once you get it adjusted you will have learned a bit more about your machine,