Suggest you swap the core with one in a known working installation, and see if the problem migrates. Try the other core with your installation, too. It is fairly easy to see where the problem is if the problem moves (or doesn't). If you think your GPS is the culprit, swap in a known working GPS puck and see if that cures it.

Finally, if your shortened the leads on the GPS antenna, or the flarm dipoles, it would be worthwhile going in and checking your soldering.

2D

Flarm guys finally got back to me and denied a replacement. My only option is to send it back to Williams Soaring for yet another board replacement. I am not at all satisfied with this, but apparently have no other choice. I will post again once I get it back and find out if it works.