How to Fix a Stubborn Sliding Door with a Sagging Beam?

Hey everyone! I need some help with my parents' sliding door from Andersen. It's super hard to open, and it seems like the issue has been getting worse over time. A professional from Renewal by Andersen checked it out and suggested that a slow leak from a tub on the second floor might have caused water damage. This has led to the beam above the door sagging, making it almost impossible to use the door. I'm looking for advice on how to best go about fixing this without breaking the bank. Do we need to replace the whole sliding door and beam, or can we just swap out the beam? I've attached some pictures of the door as well. Thanks!