I recently moved into 2 yr old house with Weather King (made by Ruud or Rheem?) 92% forced air furnace. The basement is unfinished & I have noticed supply ductwork popping, apparently due to expansion/contraction, on heatup & cooldown. This wakes me in the middle of the night. I would like to remedy this annoyance before finishing the basement. Posted answers mention S-lock, cross breaking, & possible insufficient return air. What does this mean, & what other methods can I use to solve this?

((Posted answers mention S-lock, cross breaking, & possible insufficient return air. What does this mean, & what other methods can I use to solve this?))

It means that one of those item above is causing the problem.

S hook combines two pieces of duct together.
Cross break means that you remove the offending duct and cross break the metal with a metal break made for that job. A cross break looks like this X length wise on the metal from end to end. It causes the metal to have a seam and that stiffens the duct.

Return air. When you have to small of a return air duct the furnace actually sucks or causes the duct to partially collapse. When the blower turns off and on it allows the duct to move causing the pop.

Now you know.