Yes, the brake adjustment is accessed by removing the cover plate on top which reveals the adjustment nut. The right hand cover is the seat bracket on early WD's, but on late ones the right cover can be removed without removing the seat.
The external square headed set screw with jam nut that is on the back side determines the clearance between the rear shoe and drum, i.e. it divides the clearance equally when brakes are not applied.
To adjust the rear screw turn in snug and then back out 1/2 turn.
When adjusting the internal nut, maintain at least 2" of pedal travel or the brake lock will not engage. All this assumes that "doing the brakes" means adjusting them. If they need to be replaced, I suggest you start soaking the pin at the bottom weeks in advance with diesel fuel or liquid wrench. Pin can also be drilled, tapped and then pulled. Remove front band first. Check drum for cracks.