If your mechzilla goes Alien mode.. don't wait. Get to the screw before the mech comes apart.
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Here's the setup.. the pan head screw holding the magnet can work free.
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It's kind of a PITA because that spring washer doesn't fit through the plastic shell easily, so if it escapes the magnet pole.. it's a PITA to get on the magnet, through the hole, and aligned with the coil at once. I had pulled it out, bent it a bit narrower.. and by not aligning it with the coil, I was able to get it halfway through the hole, and force it through with the magnet pole... then get it in the coil.
But note when trying to put the screw back in, you have to lift the coil (it's otherwise not supported) up some to get a nice squared fit for the screw. You can't hold the magnet to keep it from spinning either, but the spring washer is there I think to help get that tension for you. Recommend putting some locktite on the screw when you re-install it.
Probably easier if you took the mech off completely, but I didn't see an easy way to get to the screws holding mechzilla on.