mk421

I have an FC7000-75 plotter with which I use Flexi 10 to print and cut with. I am trying to cut a job I printed the other day, but the plotter is not cutting in the correct spot. It is starting the cut sooner than needed. I tried doing a factory reset, adjust the ARMS axis' and changing the type of registration marks, but nothing works. I also cleaned off the sensor with the some rubbing alcohol. I have had the same thing happen on an FC8000 at my last job. We ended up replacing the sensor for the FC8000, which fixed the problem. But I am wondering if there is a way to fix the problem without having to get a new sensor. Thanks.