I have a DX-440 which has served me well for many years. Recently I
let the batteries run down; one of the D's had even leaked a little.
The radio was completely dead even on the AC adaptor. I replaced all
the batteries, including the two AA's, cleaned visible contacts (I did
not take the radio apart to get at the other battery contacts), and
the radio came back to life (with all memories erased), but only on
the AC adaptor.

If I try to use batteries only, when I push the on button the clock
display temporarily fades, but the radio does not come on. As soon as
I plug in the AC Adaptor, the radio works perfectly.

Any suggestions would be much appreciated.