Avioniker.
Yes the wing - body fairings have caused a few headaches, I just listed common causes that my company is coming across at the moment. It seems to vary across companies as to the current fix.
Nr Fairy.
I find that reporting something to Cabin Crew is not over effective, by all means if you see a large fluid leak, or a lump of airframe depart ship, but they are probably well aware of vibration, having been on the aircraft several times before ! believe me they are usually the source of the first complaints.
G-ALAN
Engine Vibration is usually detected by instrumentation long before it is felt by anybody, and is normally only one engine, normally at Take-off and Climb power settings, it usually settles in the cruise. This goes for both CFM & V2500. Vibration that is noticed by Pax is usually airframe.