how to access wiper motor on 560sl 1988.

Look above the brake pedal on the firewall. Look for three nuts surrounding a shaft, that connects to the wiper linkage. The nut on the linkage shaft is difficult to remove but does come off. The three nuts should come off easily. Once all nuts and the linkage are removed, you open the hood and in the engine bay, you can remove the motor. It is a tight squeeze, but it will can come out, you might have to remove the wires and plastic covers.

https://www.benzworld.org/threads/1988-560sl- wiperblade-motor-replacement-help.1838090/