Since you have broken needles and hit the sole plate a number of times, your machine probably needs to be timed. This will require a trip to your sewing machine repair shop. I had that happen when going over a very large seam and part of the needle was broken off on the inside. It sewed OK for awhile, then began hitting the sole plate. I took it in and he re-timed it (and removed the little piece of needle) and it works great now! Good luck!