Wonky bobbin tension in my 440
It has been almost a year since my Berenina had her last clean & tune up but I was hoping to go just a pinch longer. Today she started having loose understitches. I cleaned the bobbin case, oiled her, changed the needle & rethreaded her...any other suggestions to help her along? Luckily I have a 330 as a stand by but I just love that 440 and hate to use anything else.