After removing my N15CS engine from the frame, having loosened all engine cradle fixings, the gearbox started leaking. Thought at first it was coming from the selectorcam fork spindle hole, but after washing down & sealing that, still leaking. Seemed to be at the very bottom of the box, so assumed it was inside the lower mounting pivot bolt hole. Upon withdrawing said lower bolt, still could not see any obvious leak inside. It was whilst wiping the oil from the right side of the lower mounting lug face, one can see oil oozing from little pits in the machined face which mates with the engine cradle. How on earth the oil communicates from that machined face & the inside beats me. The clue was that it was OK until I loosened that lower pivot bolt, so once the bolt is retightened I assume it will stop. A really odd problem. Never seen such a thing before. Just wondered if anyone else has found their lower gbox case to be porous too?