I've offered to help fix the doors on a 1950s~1960s hangar. Its only a small steel framed agricultural type building to house 2~3 planes. The side-to-side sliding doors are top-suspended, with steel frame and trapezoidally corrugated steel cladding.
Age, use, and almost certainly lack of maintenance means it is almost impossible to move them now. They don't appear to completely resting on the ground but there may be intermittent contact.
I imagine wear and tear of the runners and bearings is the issue and I feel it must be fixable for not too much money. But I haven't been up on a ladder to have a close look yet.
Its a long shot I know but just wondering if anyone has experience of such things, in particular:-
a) Is the suspension system typically a square 'C' sectioned runner ?
b) Might the rollers be height adjustable for wear or fixed size ?
c) For runner and roller repairs would it be necessary to remove the door completely or could it be done with the door jacked up ?
All experience appreciated 
Gerry