Hey Guys,
I do have the same issue with my Agilent U1273A as well. An Agilent spare for the U1273A is not available, they exchange the whole meter for a fixed price. I did a lot of testing and soldering. What I can tell you for sure, only the SSD1303 Oled display will work ! Everything with SSD1305 or higher has the mirrored image, cause the driver is different to the SSD1303.
Unless you find a NOS somewhere, it will not work. As OLED change very fast in China, I did not find any resource to get a SSD1303.
Hope this helps
DPX