Hi Bruce,
I will explain what had happened to me. There is an inox curve about 20cm starting from the engine side, connecting the engine with the pipe going to the exhaust tank. There was a very small leakage from the downside of this inox curve. To see if this is the cause you definitely need to remove the pipe and have a close look.
I hope that might help.
BR?
MIke
Michail Karantakis