Finally got the door out; you have to find one of the upper holes with the vertical locking bar that secures the slider in one of the part open positions to gain enough clearance over the bottom track to remove the door. Otherwise it's just a household roller door set up, right down to what appear to be plain
steel needle bearings in the rollers !!...Greasing the track is probably not the go as it would promote sliding instead of rolling; but if it works for you spray away! New roller assemblies with SS sealed bearings were about $8 per...Cheers