Problems with SME V Tracking

I just purchased an AVID Volvere/SME V setup, and I'm having problems tracking normal weight LP's. The arm tracks 180-200 gram LP's flawlessly, but on nomal weight vinyl it "sticks" at about 3" to "5" into the LP. Very frustrating to say the least. I have a Benz Ruby 3 that I've set tracking force to 2 grams, slightly over the recommended 1.8 grams. I've also adjusted VTA which initially helped somewhat, but I just can't "dial it in."
Thanks in advance for your comments/suggestions.
The SME has an unusualy thick armtube. With shallow cartridges it can sometimes catch on the armlift or on the edge of the platter. On thicker lps the armtube runs a little higher thus clearing the lift. Check this before doing something radical.If that is the problem up the VTA or get a spacer between cartridge and headshell.