[Test-Equipment] Hexem E-I-R Meter question

[ab6mt]

Model 110D Hexem E-I-R meter is a solid state (analog) DC multimeter with
extended ohm scales and current measurement functions.  It has a
center-scale meter: positive voltages and currents are read from center
scale to the right, negative from center scale to the left.  The resistance
scale is conventional.

Two zero adjustments are available on the front panel, one a "zero" knob
connected to a ten-turn pot, the other is a course-zero screwdriver
adjustment.   It apparently was designed for use with (2) D-cell batteries
and (2) D-cell sized mercury batteries.  Four D-cell alkaline batteries have
been installed and it seems to be working.  However, when switching between
volts and ohms, the course adjustment must be readjusted with a screwdriver
to obtain meter zero.  Normally the volts and ohms meter-zero should be set
using only the fine-tuning "zero" knob.

Does anyone have any experience with this meter, and/or have an instruction
book?  For example, there is an unmarked adjustment inside the cover which
hope-upon-hope could be a balance adjustment.  Of course there is no point
in tweaking it without better information.

TIA

Bill
hbcs at sonic.net