1997 TRX300FW leaking oil from cylinder head

I bought this TRX300FW used last year and it is a great reliable machine. Yesterday, I noticed that oil is beading out of the rubber plug on the cylinder head. It looks like the previous owner used some junky sealant as a gasket, which is now flaking and cracking.

I’m not mechanically inclined, but I’m good with directions. Does anyone have any recommendations on how I can easily fix it? Can I patch the sealant with new sealant, do I need a new rubber plug or do I need to install a new gasket? I’ve searched for hours and I cannot find a post describing similar symptoms.

Any help is greatly appreciated.

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1997 TRX300FW leaking oil from cylinder head-imageuploadedbytapatalk1441048990.072966.jpg