BSA M34 -12 oil leak.

[tonyairconchap]

HI team,
I have a small oil leak coming from the timing cover. Its on the thread on the plunger that screws into the cover. Big end oil supply i guess.  The oil creeps out through the thread when the bike is running. There is a small oil return hole towards the top so am unable to put any paste on the thread. Cant really see how to cure the leak. I have attachec a couple of pictures so you can see what i am talking about.
any help from you would be gratfully received
thanks
tony