Hi there, My wife has been using the 9020 Singer for quite a while producing some lovely work. Last week she was filling a couple of bobbins, forgetting to disengage the drive to the main shaft. When she returned to sow, the machine is running in a very labored way as if something is causing some resistance. I tried clearing thread from below the needle plate. There wasn't too much there but it hasn't made any difference. Any ideas?