Check your bridge spoiler for any movement. I was chasing a squeak for ages which turned out to be the bridge spoiler moving slightly. I secured mine with Teflex and it's been silent ever since.
I couldn't get any of the screws out and they were all spinning round so opted just to bond it on at the mounts.
Check your hockey sticks too as the stupid little fasteners can work loose. Also don't over tighten those as you can break the plastic!

These being loose at all also causes squeaking. Best soak them in WD40 for a while before trying to tighten and you'll need to be creative as it's a round nut with notches at either side. I used a little screwdriver and used a hammer to

them round. PITA!
Stuart