I have the Cardas Sweep as well and would agree that the blanks are certainly not the be-all/end-all in setting anti-skate. That being said, in my setup the arm moves very, very slowly in the "outer" blank and hardly at all in the inner blank closest to the label. If yours is literally shooting across the blanks and skipping towards the label I would think you might try increasing anti-skate, not decreasing it.
Ultimately, though, you want to set by ear. There are some great posts in the archives here from Doug Deacon with respect to setting anti skate by ear-do a search for those.
Finally, if you don't have a digital stylus force gauage or protractor, invest in a cheap one (they need not be expensive). Even though a dealer has set it up, things can get out of wack, particularly if you've transported the table home from the dealer's after setup. You have a nice table/arm/cartridge and proper alignment/VTA and antiskate are critical to realizing its potential. There is a ton of good info easily available here and at vinylasylum that you can quickly pick up on to get things in order yourself.
Ultimately, though, you want to set by ear. There are some great posts in the archives here from Doug Deacon with respect to setting anti skate by ear-do a search for those.
Finally, if you don't have a digital stylus force gauage or protractor, invest in a cheap one (they need not be expensive). Even though a dealer has set it up, things can get out of wack, particularly if you've transported the table home from the dealer's after setup. You have a nice table/arm/cartridge and proper alignment/VTA and antiskate are critical to realizing its potential. There is a ton of good info easily available here and at vinylasylum that you can quickly pick up on to get things in order yourself.