ah .... success! I fixed it. The ut videos didn't show you how to start this. But it was kind of obvious as you went along. You have to be holding the spring stationary with one of the bars when you loosen the set screws. I had the bar in place but didn't realize that even a "loose" spring still has a lot of tension. When the set screws were backed off the spring suddenly snarled and went aggressive. I was able to hold onto it however with one bar. I then used the other bar to tighten it one turn then re-set the set screws. I repeated on the other spring and opened the door. It responded like I was a drill sergeant, stopping, and staying, where it was supposed to. I know I saved at least a $100.
About the bars, I said earlier I found the best price ($13 a pair) on Amazon? Wrong. I went to home depot and while looking for the garage door stuff I inadvertently passed a bin with steel bars. One bin had 36-inch bars that were 1/2" diameter. The instructions call for an 18-inch long 1/2" diameter bar. I bought one and cut it in half and it worked perfectly. Price: $5.50 for the bar so $2.25 each. Amazon $6.50 each.
I now understand why this isn't recommended. The potential injury is most likely not from the spring but the bars. If you lose control and you're dumb enough to have your head close to the bars they can suddenly go ballistic and give you a permanent headache or possibly break your arm or worse. But my only goal was to tighten the springs one turn and, being very careful, it worked.