The noise is cannot be caused by anything beyond a simple mechanical issue. They tend to be noisy the first 2 weeks of use, so on a new pump this can be normal, the pump needs to wear in. If it is an older pump the bush bearing is the usual culprit, be sure it is pushed in all the way, if it is, try prying it out, turning it 180 degrees and reinsert. The bush bearing is a collar around the hole.