by d_goldsmith » 15 Dec 2006 0:34
If he was grabbing from the top, the wrench wouldn't be able to go past the pins.
The amount of tension you get has to do with the pressure you exert on the wrench and the leverage. So if the arm that you press on is very long, and you push at the bottom of it, you have more leverage and would be more likely to over tension it, which would explain not being able to move a pin. However, if the piece you press on is long, and you push closer to the plug, you have less leverage, so that part can't really be to long as long as it is functional.
The part that goes in the keyway though, I don't think it has much to do with it unless it is blocking the pick or catching on something inside the plug.