get your owners manual that came with the machine out go through the maintenence section and give the machine a good cleaning/oiling, then a new needle, rethread and it will be like new. most machine manuals tell you to clean it every time you change the bobbin and change needles with every new project or 8 hours of sewing. most people do not bother...then wonder when their machines are not happy machines any more. i think we have probably all been guilty of this at some time. but you need to think of your machine like any power tool, it has to be taken care of if you want it to last and take care of you.