I have an 1130 bernina

Question

i have an 1130 bernina and love it! with all fabric types the top material is not moving along with the bottom material when sewing seams. the lighter fabrics are puckering and the seams are anywhere from 1/4" to 1' SHORTER ...tried changing the tension, lengthening and shortening the stitch, using different needle and needle sizes,etc...could it be the tension on the presser foot is off and if so how do i check it?