Slacken the rear wheel spindle nuts and the rear brake anchor pin, undo the lock nuts on the chain adjuster screws. Screw in the adjuster screws a little at a time to force the rear wheel spindle backwards. To keep the wheel in correct alignment it is desirable to count the number of turns given to each screw so that they may be turned a similar amount. Tighten up the spindle nuts before checking the adjustment. The correct adjustment should allow ½" up and down play on the lower run of the chain. Always check in several places in case of variations. Tighten up the lock nuts after making the final adjustment and finally make quite sure that the brake anchor pin is tightened up fully.
N.B. - Always refit the spring clips to the chains so that the closed end of the clip faces in the direction of travel of the chain. The primary chains are endless and have no spring link.