[mikethedruid]

I don't have the schematic for your radio in front of me, but a couple of things occur to me. There may be condensers involved with the drifting bands that are drifting in value as they heat up. These may be ceramic or mica types. It may also be resistors involved with these particular bands. Look and see what resistors and capacitors are used only for the bands that are causing problems. Since your radio is only single conversion you don't have the problem of first setting a second IF or third IF and aligning backwards toward the front end, but only have the one IF to deal with.