The Kemp system seals on the larger diameter of ET165AS immediately below the nipple carrier. Time Traveller's seals on the smaller diameter, which I think is a standard spoke size. The Kemp system works quite well (better than the original for sure) and works even better when ET168 is right way round. Don't ask. I still have a leak in that area, or at least a leak that collects there. From experience I wouldn't be surprised to find that the source of the leak is the front left head stud. Vincent oil leaks too move in mysterious ways. I'm going to try TT's device - easy enough to make a new modified ET169 - next time I have the timing cover off. Which I hope won't be any time soon.
I have wondered if some of the "moistness" is fling from my Scott-oiled chain at the gearbox sprocket, but since the level of chainsaw oil in the Scott-oiler goes down at a glacial pace, I can't see how. Any opinions?
The chain incidentally is a bog-standard JWIS, and has required adjustment precisely ONCE in 18,000 miles.