Thanks for the replies.
Top Bunk,
I know the a/t balances epr, however the 747's (49 of them ) we have are aging badly and whilst the epr is balanced the n1's are never in sync and its not every airframe that suffers from this cycling vibration.
I did wonder whether disengaging the a/t and having a play might be more beneficial than the large thrust lever movement required to move out of the FADEC gate.
The solution the more i think of it rests in a seat cover than has a material to heavily dampen vibration, any ideas here would be great, neoprene seems a popular choice on the net !?