WASHINGTON — Problems with an upgrade installed on some Lockheed Martin F-35 Joint Strike Fighters rolling off the production line have now disrupted plans to incorporate those upgrades on existing aircraft, and the F-35 Joint Program Office does not have a date for when those jets will get the much-anticipated retrofits. The F-35 program “was scheduled to begin TR-3 [Technology Refresh 3] retrofits in April 2024 with the intent to modify 149 aircraft over the subsequent 12-month period,” JPO spokesperson Russ Goemaere told Breaking Defense. But now, “[t]he Program is working closely with F-35 customers to establish a new start...