Are these too new to talk about? I suspect I need a new motor. It was Grandpa's and I only saw it work for a hot second when I was a little kid.
I had a similar one years ago. It had the simulated waterfall and stream. It even had a recorded loop of rushing water and bird sounds. It was given to me and did not work. The pins that held the (motion) rolls were broken off and the belt that turned them was deteriorated. I don’t believe you can buy parts for them so it’s best to do what I did and make your own. If the motor works you should be able to get it going again. An electric supply store should be able to duplicate the motor. A little JB weld and some ingenuity. If it’s beyond hope a pin ball/arcade machine restorer could fix it easily.