I seemed to have the same problem - z axis works sometimes and not others, plus it reverses up/down direction occasionally. Tried your diagnosis directions (VERY HELPFUL) and found broken (red) wire on stepper motor above z axis where wire enters the motor.....Do you have a fix for this? My machine ...

Thanks Guys, I will try the double red base and allen key ideas. I'll keep you posted! I have 80 cars to cut out in the next two weeks! Whew!

My IMS CO2 Car/F1 Car fixtures are really frustrating me. Since the base and end blocks are made of aluminum, I cannot tighten the thumbscrews enough to keep them from working loose while the car is cutting out. I even retighten/snug them between sides. This has happened multiple times. I was having...