Ideally, the swash is level throughout the entire range of motion. That said, it often ends up tilted slightly one way or another to compensate for balance, or some other issue. If I were in your position, I'd fly it and see if it's way off beofer adjusting anything. You make it sound like you bought it used, completely setup, and if that's the case, the previous owner most likely trimmed it into that position to get it to hover well.
If you want to adjust it, the best way to do so is mechanically by adjusting the linkages. On your heli, the simplest way to do it would be to lengthen or shorten the rod coming off of the elevator servo (move the right stick on your transmitter up and down, the servo that moves is the one you adjust the linkage coming off of) until the swash is level.
A good place to go for info on Raptor setups is http://www.raptortechnique.com
. They have detailed instructions on how to setup Raptors, and will help you a lot.