I too have a 103 motor and saw the same thing in the same spot as you've just shown. Resealing the front cover did the trick.
103 head gaskets leak from the rear(passenger side) and when they do, you'll see oil on the ground just below that general area.
1991 300-SEL - Model 126
M103 - SOHC
James Madison - Oppressors can tyrannize only when they achieve a standing army, an enslaved press, and a disarmed populace.
Liberty Firearms Training - After years of trying to regulate California criminals with a never ending stream of gun control laws they have still not given up with the belief that if they make something a crime that criminals will miraculously start obeying the law.