Hey Bev, From my experience on the refurbished one you will start to get alot of thread breaks and fraying. Of course, I always change the needle first and when that doesn't work I check the thread roller. The roller would have a groove or nick. They are easily to replace and I have replaced the pinch rollers also which are the red rollers that you flip up because they can wear grooves also. It just puzzles me that I can run both machines at the same material thickness or in some cases I have to run the refurbished one point higher and it continues to groove out rollers. Seems like the thread feed motor isn't feeding the proper amount according to what you place the material thickness. Janet Jones Burke Sporting Goods 703-239-9000