I had the drive belt on my Great Dane replaced last week. Today I was using it on a lawn, everything was working fine. Then, all of a sudden the right side started to not respond very well. And it progressively got worse. It felt like something was slipping or something. The left side continued to work fine. A talked to a friend who said that the drive belt is probably loose and I need to tighten it. Does this sound right? Any tips or suggestions? Thanks.