Sewing machine problem

Hello! I just wanted to ask here in case anyone knows , i have a viking sewing machine and recently its been skipping stitches? I have the stitching in between 3 and 4 and ive tried other numbers but no use

Hello! I just wanted to ask here in case anyone knows , i have a viking sewing machine and recently its been skipping stitches? I have the stitching in between 3 and 4 and ive tried other numbers but no use