And even if you do, you're stuck with 1970's
Radio-Shack grade op-amp design.

Actually I opened it hoping I could replace an op amp
but there are no ICs in it at all.

You're probably not looking at quality, then. The 70s
was [sic] awash with grotty discrete kit.

To the best of my knowledge, this equalizer was not an RS design. It came
from a little company called Metrotech, and appeared as a Popular
Electronics construction project. The same circuit was later used by BSR for
a 12-band equalizer.

It should be noted that, even in the '70s, IC designers were still "finding
their way" with respect to op amps. And there are plenty of current
designers who would not agree that ICs are inherently superior to discrete.