Thanks for the info. Changing the boom mounting position was something I didn't try but did think of. Not sure why, I guess it didn't make sense that it would cause it, but when do these things make sense. My issue only seemed to occur when the Blackshark fuse was mounted. Was ridiculously smooth as a pod & boom. Hirobo actually sent be some new head dampers that were meant to solve the issue but unfortunately they did not.
I've always thought it was a harmonic issue and have tried a range of things to try and fix it. I would say that I had everything so finely balanced it would match anything that factory would produce.
Unfortunately I had crash with my Eagle not long after my last reply and been feeling a bit flat after that and put the Eagles on the shelf for a while. Plan to build a couple of new Blackshark fuses hopefully soon and will try changing the mounting when I get the chance. There are space restrictions using the fuse but I think it should still be possible.