Gently tap the stuck part to see if it pops back. If it does, try to spray some lube around it and work it a few times. That's the bandaid.
You should probably pull the door card and remove the handle to clean it up and lube it. It isnt a hard job. It is a little bit of fidgety work getting the rod off the ball, but I have found warming the nylon fitting with a heat gun helps a lot. Warm it to take it off the ball and to put it back on the ball.
And be prepared to snap a few card clips. If they are original they are really fragile.