I looked up your receiver manual online. It says to use the CD inputs for turntables/pre-amps.
My past and current receivers have ALWAYS had a dedicated "Phono Input" with a screw to attach the grounding wire. Not sure why the Pioneer Elite doesn't. It just says to use the CD inputs.
I've...
Have you examined the turntable cartridge? Maybe disconnect the headshell from the tonearm and check for loose wires or dust build-up. Blow on it with compressed air.