Thanks for the reply. I did have greater success selecting and copying an 'isolated' image from the PDF (opened it in Affinity Photo IIRC), but it was not a vector, which is what I need. The layout in the vector files is really weird, as none of the images within the smaller panels appear to be 'locked', or available as a separate image or even as a panel group. When I zoom in, none of the lines connect, though they appear solid when not zoomed, and there are little boxes at the end of each line, which if selected, move the line.
I've never used AI, and am just beginning to get my head around AD, which I really love so far for what I am doing {GUI/panel design for virtual and eurorack-modular hardware instruments/effects}. I've just been lazy (and kind-of embarrassed, tbh) about contacting the vector maker, and asking what do I need to do, which is my obvious solution.