What could be wrong?

I was playing an LP on my turntable, changed LP's, cleaned the stylus with my trusty Zerodust and proceeded to play the next LP only to discover that the volume on the left channel was reduced noticeably. At first I thought that maybe one of the tubes in my preamp was dying, so I played a cd on my digital player and everything seemed fine. I checked the DIN and RCA connectors on my tonearm cable, and everything seems ok. I turned the phono preamp on and off and still the left channel volume was reduced.

Do you think that my zerodust gel cleaner somehow damaged my stylus? Or could it be that my phono preamp suddenly malfunctioned? I'm a bit baffled as to what is wrong...

Any suggestions?

calgarian