1995 Mercedes Benz S320 windows

Electrical problem
1995 Mercedes Benz S320 6 cyl Automatic 148000 miles

The driver side window goes down fine but will only go up 1/4 inch at a time. Have to press the switch over and over again until the window reaches the top. Recently the passenger side started doing the same. Is this a switch problem? The car is seldom driven and the window is rarely used specially the passenger side.