Are you sure the screws are threaded the same? I know there are two threading standards out there (US and metric I believe) and even thought the D-Sub connectors themselves are the same, the screws may be different. I know some companies like Pro Co include both types of screws with their snakes. It wouldn't surprise me if Apogee was US and Digi was metric. It seems odd that one side works, although it may well be that that side is stripped or something.

A trip to the hardware store may be all it takes.

-Duardo

Apogee's customer service replied to my frantic e-mail within a couple hours, and Leon said he'd send "Apogee snake screws that would be appropriate." I sent a return e-mail asking what he meant, but so far no reply.