when last was it been serviced. try and loosen it by giving some oil IF you are sure it is needle bar.way to check is by firstly give yourself a reference as to where needle bar is at moment in relation with handwheel before you loosen the needle bar clamp.if needle bar move easily after loosening you will have to resort to other mean of determining problem,could also as well be some cotton stuck in hook that will give same indication
johan, May 2013
