how to reasemble mira shower mixer unit?

i have a gravity fed mira shower unit, i have replaced a washer on the mixer unit as it was dripping at the shower head, unfortunately the cams on the mixer unit fell apart before i could take note of the positioning of the cams and now i am not getting the correct mix i.e the flow cannot be regulated properly and is running far to hot, can you give me any hints on the correct positioning of the mixer cams. Many thanks in anticipation.