I have a Penn Clash 3000 that is making a scraping or "scrubbing" sound when under load. Reel has been thoroughly cleaned, gears, pinion, main gear - all in excellent shape. Can only hear it under load when reeling in. Otherwise, normal reeling it it is quiet and smooth as silk.
Is it continuous or only at a certain point of rotation? Slightly bent handle shaft would be my first bet.
EDIT: Check the pinion bearing and line roller bearing.
I had a grinding on retrieve in an 4500ssb when the rotor was at the bottom on the rotation causing the rotor to scrub/grind a bit. Turns out the washer on the top of the spool shaft was missing, which provides spacing at the bottom of the rotor's rotation.