My MR27024 is still in the neighbourhood electronics shop. The manager called yesterday to say it was ready and that he had good news: replacing the condensers (and a transistor in another circuit) made the rotary selector work. So he didn't replace the selector.
But, sigh, when I arrived and checked it out, the rotary selector was still almost entirely inoperative. (It *is* a complicated radio that he had no idea how to operate fully.) So I await their work on replacing the rotary selector as I wanted them to do three weeks ago. . . .
But there is something learnt from this. The condensers (capacitors) have a tendency to blow up and burst and my local electronics shop does not know why. ("That just happens sometimes; we see it a lot in TVs too.") If it is a matter of low power, as Terje suggests (above), then I wonder if it happens when the radio turns itself on unattended (a very common complaint about the MR27024). When it turns on like that, everything seems to be operating except that no sound makes it to the speaker, while unamplified sound *does* get delivered to the Line Out. If this oddity is a matter of coming on with low power, too low to drive the amplifier, then it may explain the exploding condensers problem.
In turn, I wonder if this can help explain why the MR27024 turns itself on.