I put a toilet in a friend's house about 6 months ago. It was the first time a toilet had been installed in this particular area (laundry/utility area) in about 25 years. The toilet worked great...that is until about 1 month ago. The toilet starts to flush o.k., then it looses steam. It actually slows down and appears as if it just swirls around. Then after a few moments the water slowly evacuates from the bowl. Where should I start???