About 15-20 years ago, I had a HH playfield fall on top of my head because I did not secure it with a wooden vertical slat box or bungy cords. It knocked me unconscious for about 5 minutes with my head and body pinned inside the cabinet. I woke up with my head bleeding, and had to wiggle out from under it so I could get leverage to lift it again. No concussion. I was experienced enough to make sure the game was off, otherwise I would have also been electrocuted as well as there is no high voltage cutoffs factory installed in GTB SS80 machines. I never made that mistake again with non-locking playfields.
Remember this lesson collectors.
People have made this mistake many times or think the playfield will not fall.