I need to replace the rollers on the bottom of my door. The door is a vinyl door and looks to be a preassembled unit. I can see no screws anywhere in the frame. I have removed the stop at the top end of the unit. I have retracted the wheels all the way. The door and frame are each one piece with nothing that can be taken apart. There is nothing on top of the door in the frame nor are there top rollers of any kind. I am able to lift each end of the door, one end at a time, enough to clear the frame at the bottom edge if I slide the door to either end. It appears that the bottom frame edge is higher in the middle than at the ends. I measured the distance between the top frame edge and bottom frame edge and it is about 1/8th of an inch less in the center of the door than at the ends. I can only assume that there has been settling of the house and the frame squeezed so it has maybe buckled. You can tell there is a problem because the door opens hard at first, then gets easier. When closing, it comes easily at first and then gets harder at the end. The only solution I can see it to shave some off the bottom frame edge to allow clearance. The problem with that is I don't know if the piece is solid or hollow. I would rather do something else rather than damage the look of the frame. Any ideas would be appreciated.

I have a powder room on the first floor at my house and the door all of a sudden sticks at the bottom. The first floor does not have a basement under the powder room but only sits atop a crawl space that is about 18" high from the ground. The room was built in 2002 and until this week has been fine. Monday morning the door was working well but by Monday afternoon I noticed it hard to close. The humidity has been high here near Philly but since 2002 it has never done this before. Anyone have any suggestions how to fix it before I take down that door and shave the bottom? Thanks. Rich