Sounds like you narrowed it down to the phono stage. While you are working on that, if your 2001 is the one I think it is, the silicone damping fluid in the pods can evaporate over time. This happens so slowly it is hard to notice. Check and see. Another cheap yet effective tune-up, the Origin Live belt and Cartridge Enabler. Finally, if you have an old aftermarket power cord laying around open the motor and solder it in place of the factory black rubber power cord. Any aftermarket cord will be an improvement. This was my very first turntable mod when I did it on my Basis some nearly 30 years ago.
Nice table, you can do a lot with it. These things won't cost much but will sound like they did.