I have a used x-carve 1000 with the gShield and Arduino. I bought the machine used and I added the Zero probe. But the machine seems to glitch out. It is not consistent. When carving a 1" circle 1/2" deep it keeps drifting in the Y-axis, for every depth pass in in Z-axis. It keeps inline on the x. When the carve is finished the (0,0) start has also moved in the y-axis as show in pics below. Please Help!!!