AKA gray asphalt wrote:
The door is about 8 years old. It doesn't have any plastic wheels or
anything other than what looks like a tongue and groove between the door and
the frame. I removed it once and cleaned it and put in some teflon stuff. It
worked for about 6 months. Now it is really sticky and cleaning didn't help.

What should I do?
Are the doors usually a standard size? It's a tract home.
I'm cheap.

I'm retired and that can make ya cheap (and creative). If your
door is anything like ours its toast. There was a wheel and it wore
out. The alum base was (center hump the wheel rode on was pretty much
gone. My improvisation has lasted a year and is going strong. If I can
find our camera (granddaughter usually has it) I'll take a picture and
post it later today. (It's 7:00 AM in Calif) See if you can visualize
this:

I picked up a roller assembly that is normally used on heavy closet
doors. Its about 3" tall X 1 1/2" wide X 3/8" thick with a nylon wheel
(about 3/4" dia) at one end (protruding about 1/4 ") and an adjustable
screw for the wheel at the other. At the wheel end there are two
flanges with holes for screws and mounting. I drilled one hole through
the upper left corner and used three screws to fasten it to the outside,
closest to the door frame and of course, the bottom. The beauty is that
once in place, its adjustable. The nylon wheel is grooved to ride a
hump but in this set up it rides on the outside edges.