Thanks for the tips. They stimulated me to hunt around in the shed for some small bulbs I had used to fix an indicator light in a Mazda cruise control master switch.
Turns out dash indicator lights from an old Mazda fit right into the circuit board of the receiver display. Voltage was about right - 14V marked on the base of the receiver bulbs is close enough to what we all know autos run on. And since both the receiver and the car were made in Japan, they both are going to be metric. So, presto! Didn't cost me any more than twisting the handle of the screwdriver. I did have to free up the front display to get room between a heat sink and a capacitor to screw the bulbs in. Even better, the dash bulb bases use a bayonet socket so in the future, I can just buy replacement bulbs at Autozone.
Also a good idea to meter the bulbs to make sure they have continuity. Seating and unseating them a couple of times took the oxidation off the contacts and took the resistance down to about 13-ohms.
Receiver is as good as new, now!
