I will guess your window lifter is brokened or torn .LIFTER is a part raise the widnow up & down power by a motor
parts is available at your local Mercedes dealer. have someone replace it for you.
it will need a good experience tech to replace it because it need a lot adjustment to fit the hard top & soft top seals.
hope this help.
[This message has been edited by MB STARS (edited 05-20-99).]