Nathan,

Did you remove the gear oiler to check for any pluggage? You should be able to blow through it fairly easily, even though the squirt hole is small. Or perhaps there's a glob of something in the feed passage behind it. I don't think there should be anything dry about the gears, in any case.

Not sure that dry gears would squeal, though... was the cam checked for free rotation when the new bearings were pressed in?

Just grasping at straws...