how can I fix my Delta sewing machine? 6121 (or NM902)?

if you move the handwheel is the feeddog moving and if you adjust the stitch lenght is the stroke changing.is the feeddog set for feeding or set down for freehand working.if you answer no to any off these it could be a loose conection between feeddog and main shaft.only way is to open up and see where problem is ,that means dry parts or broken/loose connection

johan
July 2012