Biggest problem that new users have is setting the blade depth correctly. Too many incorrect instructions out there saying use a credit card or post it notes. This is 10 times too much blade sticking out of the blade holder. Also blade offset is ZERO on a Graphtec. Make sure you haven't broken the blade tip off, very easy to do. Make sure flange is holding down the blade holder.
To start with, you should set your blade depth correctly, by taking the blade holder out of the machine, and firmly cut across a piece of scrap vinyl, you will be cutting. You should only be cutting the vinyl and barely a mark on wax paper backing, Adjust blade to get there, Then put the blade holder back in machine, and use the force of the machine to get there, same results, only cutting the vinyl and barely a mark in wax paper backing. You should barely see and feel the blade tip out of the blade holder. Regular sign vinyl is only 2-3 mil thick. You only cut with the very tip of the blade. When you think the blade is so far in the blade holder, that you think it would not even cut, that is probably correct.