Early 80s Cadillac radio digital display problems

[kx250rider]

I'm an old regular in the vintage TV threads here on AK, but this is my first post here on transistor radio...

I have an '82 Cadillac Diesel with the original radio, which has an amber digital display. Several of the fluorescent display segments have failed, and I'd like to repair and keep the radio. I have read that this is a very common problem on the early GM Delco radios with digital displays. Does anyone know of a source for the display unit, or a troubleshooting method to verify that I have a faulty display vs. a display drive problem?

Thanks, Charles