At 10:14 PM 8/25/2013, Larry Alofs wrote:
>   The horizontal positioning has to be accurate.  I usually start by lining
>up the center "screw" with its hole, pressing in and turning it a quarter
>turn to lock it.  Then I check that the hooks are properly over the edge of

If you preset the fasteners to the locked position they will snap
into place as you press on them.  That snap gives audible/tactile
confirmation that the fastener has caught properly.

Yours,
David