I am doing some polish sausage with my new grinder from Harbor Freight. I am using hog casings and the large stuffer tube. I am having a problem with air getting into the casings. I am stuffing along just fine and then I hear a pop and I am suddenly playing with an intestine balloon. The only way that I could get the air out was to pop it like a balloon. The problem with that is I sometimes get a tear in the casing and I must cut it short there. My meat is kind of sticky so I added some water. That helped with the stuffing but I still get the air. Any suggestions on how to minimize the problem?