if there are not visible scratches, there may be a compliance mismatch between the cartridge and tonearm mass. The cartridge compliance can be compared to the shock absorber springs on your car... a good match means a smooth ride, a bad match means a bumpy ride where every bump in the road (LP) is felt. Doesn't mean you wont hear a POP with a good match, only that its less likely to bounce up and skate back a groove. Light arms do best with soft suspension cartridges, heavy arms with stiff suspension cartridges.