PAL / NTSC switching by jumper simply works by pulling down pin 41 (_TEST) for NTSC which is otherwise pulled up internally (PAL). On the 500 you can create the same effect by slightly bending the socket contact (for PAL). Some 8375 ignore this signal and therefore are not hardware switchable.
Why CSG even bothered producing two different chips when they already had an established way of preselecting the mode would be a good question. As would be why the made so many different versions of Agnus...
So I could also solder a wire on pin 41 to a ground to get a PAL if it isn't ignored?
And btw. is the chip by any chance socketed? I can't really see it on the pictures. I ask this because I do have an (IIRC PAL) super Agnus chip, but I couldn't manage it to work, and cutting traces on my A500 board isn't my favorite hobby, thank god I could repair that with a little blob of solder.
