Sibilence in one channel means?

I used a mintTractor and thought I got the setup spot on, but I've been noticing that when I hear siblence on vocals, that I think it pulls to the left channel - leading me to suspect that something is not correct.

Any thoughts? Azimuth? VTA?

I also hear 'lead in' on tracks (the beginning of the song starts faintly before it 'really' starts. This may also be in the left channel now that I think about it.

Thanks in advance for any advice (Dynavector 20XL on a VPI Scoutmaster w/sig JMW arm).