Here are some schematics, even about the Volt/Ammeters. They're ICL7107-type. But the displays are not specified. I attach only the best-match PDF here, there are several at the end of that thread.
https://www.diyaudio.com/community/threads/bkpreicsion-1672-3-triple-output-power-supply.363845/It seems that GW-1672, 1673 are made by Manson as PW-3023, 3033.
I experience the same problem of half a dozen names and companies for the same thing from manson, like ELV, Voltcraft, Peaktech etc., as I'm trying to repair a Manson DCS3600-Series model and there is no really useful documentation about the remote commands around.
So, generally if you want to find information, try do find out the diffent model names and google them all. And scroll through some pages to get past the annoying amazon/ebay "results". Maybe someone has already solved a problem for a "same, same but different"-model on some small private webpage or at youtube.
By the way someone here on the forum claims that BK precision has a good customer service which sent him some schematics. But that has been 12 years ago, so I guess that might have changed:
https://www.eevblog.com/forum/chat/bk-precision-good-customer-service/I assume your problem is no rocket science which would need any schematics at all. Just check if the ICL7107 or the LED-Segment is broken. In the latter case you will maybe have to change all 3 displays, if you're optically picky, as a single new one even of the same type might have a different brightness.