HP/Sony opamp IC replacement

[tinker65]

Anyone can shed some light on this opamp? parts manual says" ic wideband amplifier high slew rate", part number 1813-0299 and manufacturer code 28480 which is HP, however package says Sony BX-002.  No luck finding any information about it online so far. I am hoping it can be replaced with a modern counterpart. Thx!

[shakalnokturn]

More context such as what equipment it fits?
Very doubtful you'll find more information on the component than that given in the equipment's schematic if available.
Is it a hybrid module? If you're sure it's dead you could learn more about it by trying to remove the black potting.

[tinker65]

It is from HP 4280A CV plotter, I do have full schematics. Yes, looks like some sort of a hybrid module.  It is not 100% dead, but gain is around 0.9 while it should be 1.  This is messing up readings as reference and measurement channels have different gain now, and difference is way more than calibration pots can compensate for.

What in a world could have caused a unity gain buffer OA to develop a gain of 0.9?