The gold isn't "missing" from the after picture, it has just moved into the hole in the chassis where you can't see it

Large metal chassis (aluminum?), large glass board, screw a connector to the chassis and attach it to the board with an elastic material, heat them both up.......  

I understand how a ramp up being faster than the cool down would allow the connector to move out but not back.  i would be looking for some damage to the connector itself.  Everything moved back where it belongs except the lead, something had to give.