My machine was midway through a project and had a Z axis stall... I cleared the stall and got it running again but not it is telling me that I need to clear the board sensor. I ran through the tutorials on cleaning it and checking it, sure enough it no longer is reading the wood (even with a white piece of paper on top) I only get a 0-1, nothing higher than a 7.... so I am looking at purchasing a new sensor from CarveWright but do not know which sensor it actually is. I could use some advice please.