I ended up removing the op-amp and replaced it with an appropriate socket. In digging through my archives I had a number of older op-amps, most of which are often compatible with each other (give or take various electrical characteristics), and one that looked like it would be close was an LM741. Whereas the LM301 has 2 external capacitors, the LM741 only needed one, and the other one wouldn’t be an issue, since pin 8 of the 741 wasn’t connected internally. So I figured I’d give that a shot.
SUCCESS! With another fuse clipped in place, I could clearly see the pin moving now, and with the print head re-installed on the carriage, the print was clean and clear, in fact really nice!
