1987 Mercedes Benz 300E The fuse for my window FRONT DRIVER keeps breaking what could be the problem?

There can only be two problems. One is that there is a short to ground on the circuit. I would check where it goes through the door post to the door. The second is that the motor is shorted internally. You may try to unhook the wires from one of the connections and replace the fuse. If it still blows, the problem to between that point and the fuse box. Good luck.