I recently changed my K9 from a Karata open primary back to stock. Be sure to clean everything with brake cleaner (the grooves for the O-rings, etc. Then follow the manual for torques, etc. I think there are 6 or 8 small O-rings on the bolts, and one larger one on the housing, and another on the starter, all on the engine side. Well depicted oin the Manual. I’ve ridden several thousand miles since the switch without a problem.
Kind of a PITA to tear down the whole thing for a pissy little oil leak, but whattya gonna do? Gives you a chance to look at your clutch (measure stack height) too. I don’t know if you have experience with clutch disassembly, but using a couple of magnets gets the discs out of that basket quick like....