That is an odd leak. I know Epic have a molded cup and the fitting is bonded in after, if there is no fitting it still does not leak. Obviously Nelo drill a hole after molding to bond fitting in.
As for sealing it I would not remove the plug, it is strong enough but just leaks.
Dry it out and then use capillary action with epoxy. Put a small drop on the edge and it will suck into the small hole, should do the trick.