I'm sorry to hear you've been having trouble with the MX Antenna. I would love to understand a bit more about how you are using the device, and what kind of connectivity failure you are experiencing. With the Allegro QX re-design, we eliminated the need for an external GPS antenna connection by moving the GPS chip inside of the device to hopefully prevent this issue altogether! 

What I did was take apart the black GPS bracket, discarding the smaller piece.  Remove the two philips screws both sides from the Allegro's COM1 port (approx 1" spacing). I used the philips screws that were holding the grey stylus to the bracket (might need to be trimmed). If you don't see those philips screws, they are the same size as the ones you'd find on the back of a computer. Ask your IT department.  With the two threaded rods facing up, attach the black GPS bracket to the COM1 port using those two philips screws.  The holes on that black GPS bracket are spaced perfectly for it.  Attach the magnetic GPS.  Solid as a rock.