Ideally, your pocket door slides quietly into the wall when you open it, and a light tug on its latch is all you need to coax it into the closed position again. Ideal situations seldom remain that way forever, though, and in the case of a pocket door, improper installation, settling of the house and general wear can all contribute to sticking, scraping and misalignment. Unless your door predates 1900, it has an overhead track, and it glides on rollers or trolleys. Unfortunately, you can't always adjust them without some disassembly.
Before Adjusting the Rollers
Contemporary pocket doors come in kits that include a split stud through which the door disappears into the wall and a split header that allows access to the track. The opening in the split stud is just wide enough for the door, and to keep the door from scraping on the edges of the track, the manufacturer supplies two plastic guides, which are screwed to the base of the jamb.
Check these guides -- they may have broken or the screws may have worked loose. Replace damaged guides and tighten any screws that are loose. Check operation of the door -- if it's working smoothly, you may have just dodged a bullet.
Most pocket door issues arise from problems with the overhead rollers or trolleys, and these are adjustable. If the Force is with you, you'll be able to reach the adjustment screws without removing the split header or the split stud.
Determine whether to raise the front of the door, the back of the door or both. If the door scrapes along the ground, you probably need to adjust both rollers. If there's a gap between the top of the door and jamb when the door is closed, you need to raise the back roller, and if the gap is at the bottom, you need to raise the front roller.
Position a small stepladder next to the door, put on a headlamp so you can see what you're doing and locate the adjustment screws for the rollers or trolleys above the top edge of the door. Because this is a best-case scenario, they angled out, making them readily accessible with a screwdriver or 5/16-inch wrench.
Turn the adjustment screw on each roller to raise that side of the door. When you're done, both sides should be a uniform 3/16 inch off the floor, and the edge of the door should align perfectly with the jamb when the door is closed -- no gaps.
If the Powers of the Dark Side are strong, you won't be able to adjust the roller without removing one of the split headers. In some cases, the screws holding the rollers may have failed, and you'll have to fix them. You must take the door down to fix the rollers (or replace the rollers and track), and that requires removal of the stops and the split header on one side of the door frame.
Run a razor knife along the caulk joint between the top door stop and the door jamb and casing on one side of the door frame. Choose the side of the door toward which the screws that you can't access are facing.
Pry the top stop and casing away from the door jamb, using a stiff putty knife or a pry bar. Then, remove the split header -- a square or rectangular strip of wood running along one side of the door track. Tap the nails out but leave them in the wood -- this makes replacement of the pieces easier. In some cases, the header and stops are attached with screws, which makes things easier. Back the screws out with a screwdriver to remove the header.
Look for plastic lock levers. Not all rollers and trolleys have these, but if yours do, reach in and flip them to the unlocked position, then adjust the rollers or trolleys with a screwdriver or wrench.
If you have to remove the door to reposition the rollers or trolleys, remove the casing and stop on the side of the door that needs to swing out (at the bottom) to remove it from the track; you determine this by looking at how the rollers ride along the track. Slide the door to within a 1/2 inch of the closed position, tilt the bottom toward you and lift to disengage the rollers from the track. Lay the door on the ground, remove loose screws and replace them with larger ones. If necessary, reposition the rollers, using larger screws to secure them.
Rehang the door, if you took it down, and reinstall the split header, stops and casing, as needed. Recaulk the trim as needed and touch it up with paint.