We have a GCC plotter and it is not closing the cut completely, I have changed the knife, the biggest problem is with small dots and circles when cutting larger stuff it is not a problem but when doing small detailed stuff it is a pain to trying to separate it.
Is there a way to calibrate it? We use Flexisign Pro as software.
More likely than needing any sort of calibration, you probably need to blow the dust and crud out of the tool carriage. Just remove the dust cover on the tool carriage and blow it out with either canned or compressed air. Pay special attention to cleaning out the tool up/down mechanism.
When the up/down tool motion is slightly, even microscopically, restricted by contamination raising and lowering the tool tends to be out of sync with everything else. Ergo incomplete and over cuts because the tool wasn't up or down precisely when it was supposed to be.
Before you start turning knobs and pulling levers, give the above a try and see if it doesn't clear up your problems.