Wanna reuse some old HDDs in the new PC as misc storage and I saw this on a really old drive (the PC it was pulled out of was built in I think 2008/9). Could the discoloration on E9 be because a capacitor leaked? The discoloration seems (from this side at least) to be fully contained on the circle and off of the rest of the PCB
Not an expert here but the stain is limited to where the capacitor is located. I think it’s safe to assume the capacitor was faulty and to replace it.