My Kenmore was doing the same thing. Lucky for me my cousin was here and he has an engineer's brain and went at the problem in a logical order. I took out a part at a time from the bobbin area and he would turn the wheel and report whether it was still sticking or not. In our case the stiffness did not go away until the shuttle came out. It turned out there was a tiny rim of dirt at the very bottom of where the shuttle sits. I am still working on getting the very last of it out because the shuttle carrier part does not come off and I have to get in there with Brasso on the end of a toothpick.