[Arran]

Do you think the old A and B batteries are critical for normal operation? The power supply is tiny, which I'd expect for a portable model. Though it does have a switch for battery operation or standard AC. The battery leads are actually in nice shape, so I was planning on desoldering them from their junction and reusing the wire elsewhere.

  The "A" and "B" batteries are not necessary for operating the set on AC. Even so why would you need to reuse the wire from the battery leads, that are at most maybe a few feet in length. If they are in good shape I would leave them alone, if you need some cloth wire I would purchase some new stuff from Radiodaze, Sundial Wire, or elsewhere as it would hold up better once you start manipulating it.
   This sort of reminds me of what some radio collectors do with farm battery receivers, since they are battery powered they assume that the set is only good as a display item, and they chop the battery cables off. Why they can't just coil up the cable and stuff it in the back of the cabinet I have no idea? It's a real nuisance for someone like me who actually wants to restore and operate a set that has had this done to it, if only because they toss out the battery plugs along with the cable.
Regards
Arran