M276 valve cover seal

Hi, I'm new to this forum, but Sr Leigh super fan. I'm very grateful for the help he brings. I have a 2015 ML350, with about 75K miles.

I recently started changing the spark plugs and found on the last spark plug from passenger side some oil, not on the threads but on the side of the ceramic and where the coil makes contact. It was not dripping in oil but some oil at least.

Apparently this is not a common issue for the M276 and can't find info on how to remove and seal the valve cover. My fear is that once you open the cover I'll have to put same black sealant instead of just installing a rubber seal like in the BMW's. I did this job to a BMW with the N52 and it wasn't that hard. I'm not sure how it's done for this engine so any guide would be great. Also let me know how bad you think the problem is. I don't have check engine light and I assume leak is very low since most likely that was the original spark plug from factory. Also I notice in the coil a red hose around the coil, the rest of the coils don't have that, It's weird but looks factory, just wonder why.

Thanks all.