Tempo 2020 Zener Question

[Marcus Harton]

Hi guys,

I'm in a pinch with a Henry Radio Tempo 2020 I've got that needs a new Zener
Diode in the screen circuit of the 6146 finals. The diode stabilizes the
tube's screen voltage. The schematic shows the part is actually two diodes
in one case. It has a number on it of DZ750522a. The owners manual part
breakdown also gives it a manufacturer's part number of DDAY038001.  For the
record, I have contacted current-day Henry Radio and gotten a dust-off from
them.
This radio probably has too much silicon in it to rate true BA-hood, but I'm
having a devil of a time finding how to replace the diode, and I figured you
guys might know a trick or two about finding parts for radios whose
manufacturers no longer exist (or care.)

Neither the operator's manual nor the repair manual give a voltage value for
this zener. Any suggestions on finding the correct value? Was there a
consistent voltage range for radios with 6146 finals?

Thanks for any advice you might offer.

Marcus Harton, nz4e