An excerpt from that: (bold and underlining are mine)
"
Since the springs are winding "up" when the door is closing and going down,
the fully closed position is the most stressful on the steel and thus the most likely position at the moment of failure. This is a good thing,
because failure near the top-of-travel means that you suddenly have a large, increasing weight falling. Thus
we see the principle that you should never be standing or walking under the door when it is opening or closing, especially if you do so manually instead of with an electric opener. When the springs are working correctly, the door appears nearly weightless, but this is an illusion that turns into a calamity when the springs suddenly fail.
"
I think some of us have been saying, for years, to other HIs 'Don't stand under the door and catch it with your hands to test auto reverse.'
1) That is NOT a proper auto revers test.
2) As described above, YOU COULD GET YOURSELF KILLED, are seriously injured as you "
suddenly have a large, increasing weight falling" down.
Far be it for me to try to beat this into some heads again.
added with edit: I like this too -
"Certified technicians. / Paid certification fee to a business in the business of collecting certification fees."
Remind you of any HI association?