Just got my new pump in the mail and I have a few questions. I've used it twice and while the area just below my head (im cut) expands I can't seem to get the actual shaft to expand much if any. What am I doing wrong? How can i get it to expand at a slow even pace? I've even noticed that the left side of the area just below my head gets bigger than the right side. I'm pumping at about 4-5 mm Hg.