Accu-Rite III DRO

I recently picked up an old Accurite III 2 axis DRO, with a new 8"
scale. I bought the unit for the scale, but was told the readout
worked on one channel. When I try to use it, however, it does not
display anything on either channel. I've tired with and without the
scale attached. The readout will flicker the digits if I try to zero
the axis. Inside, there appears to be very little that could have
one wrong, as it seemd to be one main chip per channel, and not much
else.
Does anyone know what the common failure on these is? Are they
worth spending any time on, or am I best just to junk it, and use one
of the many old PC's I've got laying around for a readout?

Brad Heuver