That is probably a safe bet. Zener diodes basically measure the same as a rectifier type will, except maybe a little higher forward bias voltage like 0.7volt instead of 0.6. Reverse biased they will measure open like a rectifier until you reach the Zener voltage value. Do you know what it is rated?
Thanks for the reply will test the rated voltage with the 1k ohm resistor and 9 v battery but since it is giving me a 1.8v when doing the reverse diode test when it should be OL there is really no point in going further so I ordered the 751 zener . I have the schematic for the Memory Man Deluxe and I already replaced the dead Voltage regulator (it is a -15v), however checking more the Zener also was probably dead as well.