Thanks for your response. The fuel cap was replaced with a new MB OEM Fuel Cap just as a precaution. The small leak Code came back after about 75 miles.

I did note that when listening to the Purge Control Valve (MB # 0004701593) operate with the audible clicking sound that it stopped momentarily and then started clicking again.
Do you know if this is normal operation for the valve? Or should it be clicking all of the time while the engine is operating?
I cleaned the internal parts of the Valve today with carb/choke cleaner to see if that helps.
The Valve is the original one from 1997 so I'm ready to replace it as another likely fix if the Code comes back again.