I don't have to tell you Locky, but report it, report it, report it, and then keep reporting it, be a real pain in the butt over it, and something will get done. Recurring vibration or oscilation, in a part which really shouldn't be doing it, needs to be looked at.
I once grounded a BA 737 as SLF, when I noticed, on a climb out from Hamburg, a strangely coloured (QED essential) fluid, which appeared on the port wing leading edge. I told the FA, who got the Captain to come look. His response "Oh that's nothing to worry about" My response "I am a Pilot" His response "Ah" lol
Net result aircraft grounded at Birmingham, and my reward? A very waspish male flight attendant, on my depature from the aircraft hissed at me "Thanks to you, I won't get home tonight"
My response..... "Bite me"
So the moral is, maybe ask one of the SLF's if they notice something too, get the Captain, and the SLF will more than happily break the good news, something might get done quickly then
Tony. .(Happily grounding BA's fleet)