300 rpm motor for VPI

I am not sure how changing a motor would cause channel imbalance.  The platter is still running at 33.33 rpm.  Did you by chance bump the tonearm and/or cartridge during the motor set up?

Check the run-out on the 300pm motor pulley.  The pulley that came with my 300 RPM upgrade wobbled.  VPI replaced it. 

It seems like I saw some bass.  hearing more of my sub.  Maybe its run in issues

Agree with brf;  difficult to see how the motor could cause a channel imbalance.

However, I've found the Hurst motors to be very inconsistent;  I have some that are very noisy, others are near quiet, but they all exhibit vibration.  I believe the inconsistency is due mainly to the bearing design.

I've never been a fan of the 300 RPM motors.  Not only is the belt burn-out worse with the 300RPM pulley, but I also found that the 300 RPM motors to be noisier than the 600 RPM version due mainly to the higher power rating (7.5W for 300 RPM vs 5.5W for 600RPM in most cases):

http://www.diyaudio.com/forums/analogue-source/309925-hurst-motors-300-rpm-vs-600-rpm-upgrade-myth.html