Now we're getting somewhere.

The head gasket does not need to be replaced. This the standard upper timing cover reseal situation. The oil between the 1 and 2 runner is oozing back from the timing cover leak.

There is a special sealant from MB that is best to use at the bottom rear corners of the timing cover. Use oil on the lower U seal to allow the cover to slide back in place without moving the U seal. Replace the shaft seal while you have the cover off. Use your fingernail to see that the seal lip goes over the camshaft sealing surface to keep the seal from "folding" while you slide the cover rearward.

Good luck,