Help getting replacement rollers




Looking at the photo of the side of the patio door, there appears to be a cover. My thinking is that this can be pried off the side of the door to access the screws. It would be very strange for a patio door roller to not have any means of adjustment or removal. Something must be obscuring them.
With that being said, your patio door should still be able to lift out of the track, either from the outside or the inside of the house. Take a look at the related videos below. They may offer some insight as to how you can approach this.
As for the wheels "hanging down," use a chisel or small flat bar to help when removing the door panel. That should help give you the clearance you need.