Failed MOT and always messing with caliper adjustment but where/how do you adjust the cable either at lever or anywhere else

Copied from Miata enthusiast’s workshop manual

"Remove the plastic cover which is around the lever, using a screwdriver turn the hexagonal adjuster clockwise to reduce cable free play, setting the adjustment so that the brake is completely off when released and on by the time the lever has been pulled up by the prescribed 5-7 notches"

They recommend that the rear of the car is jacked clear and supported on stands to check the wheel drag.

Rear brakes were the only problem we had on our Mk1.
Allan

cheers, great help.
Just ordered a mx5 book off Amazon.