You will need to remove the back then you will see about 8 hex screws or small bolts on the cam. You will need to adjust them so that you get the correct reading on the chart to correspond with each inflation with the cal syringe. The cam should end up with a gentle curve i.e. not big steps. This info is in the user manual, if you haven't got one, search Vitalographs web or phone them and see if they have a spare copy
