How do you service a pocket door?
You'll need to remove the first set of trim, the ones right next to the door. 

The trims are either side at the top, this exposes the hanging bolts/wheels on top of the door. Loosen the locknuts.  Then I'd remove the two trims either side of the door (in the open position) as well (although the gap looks generous on your door). Then pull the door off the hanging bolts (a bit like opening a regular door) and slide the door out at an angle. 

The channel at the top doesn't go all the way to the frame to allow you to roll out the rollers. Slide them until they stop and pull them down at 90 degrees to remove. Clean them up and check for wear. Cleaning the channel itself is a bit tricky if folks have tried to 'improve' performance by adding lube (it just attracts debris). Various ingeniously shaped sticks with an alcohol/cleaner soaked rag on might help!

I clean everything up, (soaking the wheels in cleaner works well) and make sure the wheels are free (I might lube the wheels, but wipe away all excess carefully). I don't lube the track.