need help with adjustments of Zeiss scope

Have a relatively old Carl Zeiss rifle scope- mod. DIATAL-D 6X42
serial # 680064. under ea. cap there are FOUR screws, three black , one silver. Need to find out how you accomplish windage and elevation adjustment . Anyone out there with one of these, thanks for your help.
PS Have tried Zeiss customer service, they have no information on older products.