I have a 16x7 garage door; when it's opened, the second panel from the top buckles downward... then when it closes, it binds up putting a lot of pressure on the opener, but it does shut. How do I get that stopped? The door is only 8 years old... it's a non insulated steel door.

Did you try spraying/lubing the rollers that go in the track to free up that panel bind?

Check the wheels on the panel above the one that buckels, there is your bind. Lube, replace the wheel on that panel and you are good to go.