WD-40 is a great way to clean the track, hinges, screw and chain but it really doesn't provide long term lubrication.
I used to work in a bike shop and we would always warn customers about using WD-40 for anything other than cleanup.
Any Hardware store sells the right lubricant for your door, it's cheap insurance for $5 - 6 it costs and will last you a couple of years.
Chatter can be caused by worn screw, slipping drive mechanism or just poor lubrication.