I have a Graphtec FC7000-75. When I first got the machine last year I had similar problems to start with. Small letters were not cut on all edges, and if even one tiny corner is not cut, weeding is a nightmare. My problem was that I had the blade "dialed" out too much from the blade holder (as mentioned already in previous posts). Graphtec has a very sensetive lift mechanism that prevents the blade from lifting any farther than it needs to to move on to the next cut. This is a good feature that makes cutting faster and is less stressful on the blade as it doesn't slam down as hard on the next cut. Now I was told that when the blade protrudes too far from the holder it throws this lift mechanism off. A less than perfect cutting is the result. After I made the adjustment the problems were solved, and the cut was flawless.
The way I set my blades in the holder is to get a scrap of the thickest calendared stuff I've got, like Avery A6, that is 3.2 mil, then while I've got the blade hoder out of the machine I adjust the blade point to a position just barely visable. Then with the vinyl on a flat surface, and with the blade holder in my hand, I draw a few circles in the vinyl. When I can easily weed the vinyl, and the blade cuts through only the vinyl but only scratches the liner, the blade is set correctly.
Also, If you mangled your cutting strip, it would prolly be best to get another one. The blade is going to need a smooth, EVEN, slick surface to travel across for best performance. Don't feel bad, I've destroyed one before when I left the room after inadvertently setting the force way too high. When I came back in the room my detailed letters were in the floor, they had been "die" cut all the way through. My jobs sucked until I replaced the cutter strip.
Isaac