I am having the same problem at 25hrs and 40 min. Was carving and stopped said to clean rails (no code) did that and it started to carve but motor wasn't going. Checked everything you have suggested. Wires back of motor, circuit board on bottom, check cover switch with meter, ran options test shows motor running but it's NOT! Blew motor out tapped on it with back of screwdriver. Motor turn fine by hand. I do have another machine with 600 hrs on it so this is not my first machine.