Hi nooby-spot on with the BOV filters to clean 1st.
The other thing I would/have done after cleaning BOV filters is checking BOV closure point. I have found over time that making a mark on hex adjustment shaft-then move 1 full turn in & out and then return to original position. Yet to confirm from PWC but this has affected BOV closure behaviour.
Also I would suggest "matching" BOV closure point to within 0.5% Ng of #1 & #2...again affecting this behaviour in cruise.
If you go to trouble of swapping after all that-once removed check the valve for smooth travel by moving with your fingers.
Good luck
