Ooh, can't touch until Christmas?? That's HARD!! Good luck!!
And Moe-play around with the blade adjustment until you get it right. I generally use the tightest setting. Even when it does the thing where it doesn't even try to cut. The instructions say it should be loosened at that point or it won't work. But I once loosened it 1/4 turn at a time until the blade just fell out! Then I started over, and that time I tightned it all the way, and tried it before loosening it any. It worked! I questioned my memory of that incident until recently when it happened again. I just tightened the blade, and it started cutting again.
Is papertrey thicker than SU? If I need a new blade I'll have trouble with SU paper, but other than that, no. Really, just try adjusting it, and if that doesn't work well, trade out blades. But, SAVE the blade that wasn't working for use with paper instead of cardstock. I was tossing blades left and right until I figured this out. (duh!)
Erin in Okc