Dan.....On a stereo cartridge the Fozgometer reads channel separation and gives you the difference between the two channels via the meter, your goal is for the widest channel separation with the least amount of crosstalk and by the alignment (azimuth) adjustment you accomplish this. When both channels via the meter read the same then you have accomplished this.....with a Mono cartridge both channels should read the same because there is no channel separation, both are the same. I would eyeball it or use a small mirror. Hope that helps.
If your needing to make an azimuth adjustment but don't have a way to do so then a shim out of thin material could be used between the head shell and cartridge.....me i wouldn't stress over it, your not going to damage or ruin anything and unless your sound stage is all jacked up just let it be and enjoy