should i change the windshield washer motor?

I'd say put a meter or testlight on it first to see if the motor is getting power and ground when you hit the washer switch. If it has power and ground, and doesn't work, replace it. If it doesn't get power or ground, look at the switch and wiring. If you want to find a specialist, here's a directory link for you: https://repairpal.com/mercedes-benz-repair-in-downsville-louisiana