Commonly this is caused by loose connectors, wires or cold solder joint inside the Ground Station PCB. 

1) Remove four screws at it's back. Use a chisel to open it up on the side. 

2) Check the wires and connector for loose connection. 

3) Check the lead soldered to the video out on the board to the connector, look for cold solder joint and carefully re-solder. 

If soldering skills is not that good please open a support ticket via our website. Our CSR will assist you on how to send it back to the nearest TBS repair center.