Check if the sitting posture is correct. If leaking from silicone, ensure it's snapped in properly or replace if faulty/warped. If leaking from motor or collection cup, check for cracks or ensure they're fully secured. If leaking from milk pour hole, ensure notches are aligned. If leaking from flange hole, check posture and replace duckbill if necessary. Additional tips: Tilt pump forward 45 degrees when taking it out. Untie nursing bra detachable clip for more space. Pour milk with flange entrance upward.