Hi BB,
Received the new parts this morning and installed them successfully. The clutch body now spins truly without wobble, and the grub screws are in nice and tight (though, not TOO tight...). I believe the "screaming" noise has certainly been reduced, however I do feel as though it's still probably noisier than normal.
I have tried running the reel at a decent speed using an electric drill, to see if the 'screaming' noise was coming from the reel side of the equation, but it does not make the noise in that scenario. Only makes it when the cutter clutch is engaged. Everything in there looks to be in perfect condition though, so given the noise seems to have been reduced, I'm tempted to just leave it be...