How do you change the rotor arm on a1991 Mercedes 190e?

To change the rotor arm on a 1991 Mercedes 190E, first, ensure the engine is off and the key is removed from the ignition. Remove the distributor cap by unscrewing or unclipping it, then gently pull out the old rotor arm from the distributor shaft. Install the new rotor arm by aligning it properly on the shaft and pressing it down until it clicks into place. Finally, replace the distributor cap and secure it before starting the engine.