Originally Posted by gottdi
I am doing the parallel test to see if I can get it to pop out of the socket. I can get sufficient force. If it won't come out with the force applied in parallel there will be no chance with the force applied at 90 degrees.
Please don't miss that the leads which bring power to the brush counteract the "tends to pull toward the spring" force. In fact a brush pushed from below would raise up and then "swing" towards the leads as they became taught. In your video you had the leads undone which did not show this natural action.
Instead of / in addition to hitting it with a hammer, you could measure the force with a pull scale. The needed mass and speed of the foil could then be determined by formula. The edge of the brushes are chipped away like they were struck with great force. (or is that the other set which were damaged by over-current).
Forget the 90 deg thing. If you hit a curb going 60 it still causes you to catch air despite it being at 90 degrees to your momentum.
Finally, your approach is a bit incorrect as you CANNOT scientifically disprove a theory. It is ONLY possible to create data which supports a competing theory. I think that is why folks are somewhat offended. It is absolutely and totally IMPOSSIBLE for you to prove-without-a-shadow-of-a-doubt that this could "never" happen on ADC motors. (especially by testing a Kostov).