I haven't found anything in the manuel that explains my issue. There is loud sound when I start the treadmill and sometimes it works itself out and most times it goes in and out of loud!!!! sounds. Mostly loud. I have animals so I was wondering if getting pet hair in it somewhere could do it. . .I just was wanting suggestions as to what might be wrong and what I might could do to fix it. Thank you Diane White dileigh@sbcglobal.net