if its similiar to what i have used i believe if you spin one it changes the other to hold the exposure, and there possible might be a switch that will cause the metering to change for darker or lighter scenery so if you cant make the exposure right then flip the switch and the metering will change, then try resetting your settings after that.
also while metering these type of lenses make sure the camera is held in the most horizontal position as possible( hold it like your taking a picture but try to keep it level, hold it against your chest/stomach if it helps)
thats all i can tell you i think, synchro-compur are very hard to explain and very crazy/complicated pieces of technology