[SteveCG]

My question is this: does this chip have an intrinsic long term defect?

I have now encountered this chip twice, both in Roberts radios:
the FM3 and the Rambler II.

In both cases it is the AM section that has problems - for the FM3 low gain on both LW and MW, for the Rambler II no Local Oscillator or sign of life in the RF part either. For both of them the voltages on the pins are in agreement with the ST (a chip maker) application notes.

I've checked the switch contacts, looked for dry joints, etc.

I was wondering whether others have had similar experiences with this chip?

As an aside the only difference between the FM3 and the Rambler II seems to be that the printed circuit board is fully populated in the FM3 - with the tone button position on the Rambler II being the VHF button on the FM3. Both had a plastic frame loudspeaker and both used the TBA820M audio chip.