5r55s started losing reverse then gone!

[The-HewMan]

Just 6 months ago my wife complained about a hard shift going to 4th gear. The fix was new solenoid pak and it's been fine ever since until a few weeks ago she was attempting to back up about a 20 degree incline with 6 persons on board but it would not move. However, shifting to 4X4 low worked fine. So after that when the vehicle was empty and the ground was fairly level, accelerating in reverse she could back into the garage without shifting into low. Now low doesn't work either. I tried the sea foam (2 pints) with no change. My question is, since it started losing reverse and actually lost most of it right away but then that started slowly going away so now if you put it in reverse it basically does nothing; it would seem that most likely nothing broke but wore out. I've read on the forum where people talk about reverse and 4th gear share some components (which by the way all forward gears work perfectly) also about a broken band but can't imagine it being that because that would be quick and done with so in this case it would be something that "mostly" failed and then finally gave it up. So, has anyone experienced this and if so your thoughts please? Thank you.
2007 4x4 EB 140K 6 cyl