Right.

Well, I decided to bite the bullet and recap this one. As I removed them, I compiled a list of the values of capacitors and their locations in the cluster near the bottom of the board (near the speaker).

I found a bunch of green, gooey, yucky smelling gunk all over that area (capacitor fluid, I presume?), which I've cleaned off. Fortunately, the corrosion is negligible (except for a small amount on a nearby transistor/heat sink).

I suspect this was the reason for it not working; replace these, and it should work perfectly!

Thank you all (especially techknight) for nudging me in the right direction. Replacing it with another board which would most likely have a similar problem probably isn't a very good long term solution.

c