My knowledge of mach is limited, so I may not be the best one to answer this, but I will give you my 2 cents worth. Steppers are not closed-loop, so they have no way of knowing where they are at or if they are moving at all. With the problem you are having, I don't think a closed loop would solve anything anyhow. I am assuming for some reason, you can't just move the clamp or modify the code to avoid the clamp, and re-run the program. Using the "run from here" function might come in handy for you. I am also assuming that you have home switches on the machine or some other means of picking up on a reference point after your drives shut down. The drives are shutting down, so obviously there are no cuts in the part that shouldn't be there, and the wood is still salvageable at this point, or you wouldn't be asking this question in the first place. Hitting a clamp is a bad thing no matter what, in my opinion, and should be one of the main things to make sure is avoided before even starting the program. If this is a real problem that's costing lots of money, you/they might think of investing in a vacuum table(or a better operator). You can fabricate a good vacuum table for far less $$$ than buying one, however designing one and building it takes time. And finally, my biggest piece of advise is....If your an IT manager trying to solve not only fabrication concerns, but engineering, and maintenance concerns as well.....demand more money, or learn all you can and take your newly acquired skills elsewhere when the opportunity arises.