Working of our 169 today I removed the throttle body. The inlet manifold was swimming in yellow ooze. All cleaned out and decision on a catch tank made once and for all. That was the easy bit... I dropped my torx bolt when doing up the body, and subsequently touched it once only to see it disappear. God alone knows where it went, I cannot find a trace of the B thing I put the car over the pit and got underneath, had two lamps, used my endoscope, took video and photos with my phone and there is no sign of it whatsoever. I can only presume it lies on top of the starter. Oh well tomorrows another day to waste trying to locate it....
At least I found the horrid noise problem that I thought was the alternator isn't. Its the air con compressor. A careful dose of silicon has sorted that out too, it really does click on and off smartly now, I just hope I don't regret having dosed it this way.