Fixed an un-torqued bolt stabilizing the GPS mounting bracket. Turns out the original bolt was wedged between a firewall stiffener and the nylon nosegear bearing giving the appearance of a fully torqued nut. Virbtations from engined tests were enough to pop it free of the bearing and there was no way to get a wrench into the area to re-torque it, so I built a new brace for the GPS bracket which mounted into a more accessible spot.
New brace mounted onto the GPS bracket and firewall.