OK here's my instructional picture:
I should have said that the big knob actually has two screws (the other one is under the visible portion of the knob in the picture), and sometimes you have to loosen both - you probably want to tighten both when you put it back on.
Some variations are: one or two boards have an additional ribbon cable or two, but it should be obvious, and one board has a big brass post (for the lid screw) instead of a regular screw in one of the positions (it's visible in the picture to the right of the subject board, just under the inductor with the comment about my sloppy mu metal fix-attempt), but you just unscrew that, too.
after you do the stuff in the picture, you can pull the board out, then replace those two transistors with the new ones. The picture is post-mod. The little dots on the tops of the new transistors are there to show the orientation of the pins.
I repeated this for each of the 4 eq boards that have those transistors in Q4/Q5. The first EQ board has a different configuration, and a bunch of BC557 transistors (like 7), but no BC547. I left those alone for now, because the hum on my EQs is gone.
I have ACMP-73s, and they don't use the same transistors.
Another edit: Hopefully my posts don't give anyone the impression that I know what I'm doing
-- the transistor swap was prescribed by zmix on another board, and anything else I've done has been suggested by someone else who knew better than I did. Zero original thought here. I just thought it would be convenient and maybe encouraging to see this stuff.