This sounds like a cartridge alignment, antiskate, azimuth, or tracking force problem as some of the others have suggested. To check that, you can go through the adjustments again, particularly the ones I've mentioned, or reverse the channels via the cartridge pins and see if the noise switches channels. If the noise switches channels, you'll know it's related to the cartridge. If readusting the cartridge settings doesn't cure it, then you may have a bad cartridge.
If the noise doesn't change channels when you switch the cartridge leads(I'm betting it will), then the problem is likely a bad connection somewhere between the arm wiring and the input to the phono stage.
If the noise doesn't change channels when you switch the cartridge leads(I'm betting it will), then the problem is likely a bad connection somewhere between the arm wiring and the input to the phono stage.