there are 2 adjusters on both shoes, they are the round disc's with springs
behind them in the middle off each shoe.
no doubt you noticed them if you took the shoes off since two pins that
come out the backplate go through them which hold the shoe in place.
the spring and plate bit run in a grove so when you want too adjust it
leaver the top of the shoe along abit as if it were operating normally.
its a bit hard too describe but its quite a basic adjuster, have another
look and you will see how it works.