Very easy to adjust, and very easy to cock it up !! I did mine some while back on the advice of the MOT man.
With the engine running, wheels on the road !!!
Wheels straight ahead , place piece of white tape at 12 O'clock on the steering wheel. check for play by moving steering wheel until the wheels JUST move. place second piece of tape at new "12 o'clock". repeat in the other direction. You now have three pieces of tape on the steering wheel.
Measure the distance around the rim between the outer two. If the distance is greater than 150mm then you have excessive play.
With the wheels straight - centre tape at 12 o'clock, Undo the lock nut and tighten the screw 1/8 turn, tighten lock nut.
Do the above check again. You are looking for about 100 mm between the outer tapes, if you have less than that you are risking it being too tight and locking up. Repeat until 100 mm play is set.
MOT Manual 2.2 A
HTH