The fountain needs cleaning once in a while as mineral deposits accumulate, shading the solar cells. Bathroom cleaning solvents, such as Limaway, work good to remove these deposits. Abrasives cleansers should be avoided. Brushing 409 on the silicone rubber frog makes it look and feel new again. Rince thoroughly with water to dilute and remove any remaining solvents.
Solar cells are a glass product. They are about as brittle as a potato chip. If you drop the fountain, the impact of the fall may fracture one or more of the cells. Once that happens the curcuit is broken and electrons cease to flow.