i have the same machine & dont use the open arm that often, but when i need it....what i found works is when patching, i have to do it in stages in order to make sure there is nothing on the underside that i dont want included in the sewing...just try & 'squish' all the unwanted area away from the sewing foot...sew one seam, remove & reset the sewing area, then return to under the foot....and i use the smallest foot possible...not the walking foot as too much surface is needed to accommodate that foot...good luck