I am sure many a 7-10 was achieved by the help of lazy Mechanics. In the AMF 70 Machines I have seen many instances of the Mechanics in some Centres, regularly leaving the Pin Curtain just hanging over the back of the Cushion, this is not visible to the Bowlers but is usually detected by the noise the pins make when they hit metal. In Brunswick Centres the common reason for major pin rebounds is when the bottom of the Curtain is not positioned with a rubber end cap, so said curtain comes out at the bottom and hangs down straight instead of curved, this can be detected by the naked Eye.
willey