If you track at 2.0 you might find things dull out a bit. It's hard to give good advice not being able to hear a person's system. There are just too many variables at play.
Can you compare against a CD of the same album to see the net difference?
It seems odd that the VTA swings to one end or the other without there being some middle ground the setting must pass through.
Capacitance does seem like a logical place to look. Does your phono pre allow adjustment?