Marantz 3880 preamp question

Hello DIY Folks,

I bought a Marantz 3800 and noticed that if I turn the volume all the way counterclockwise, I could still hear music from the left speaker, although the volume is really low. This doesn't happen when I move the balance slider to the right speaker.

Could this be a dirty volume pot, or could it be something worse? I'm out of Deoxit and headed to Guitar Center to buy a can for $15 either way.

I'm also going to switch to another preamp just to verify that it's this preamp.

Not really that big of a deal in my mind, because I don't normally listen to music with the volume turn all the way down, just wanted a sanity check.