This is just in case anyone else has the problem I had - I think it's fixed. Our 2001 450 came with the Grundig Radio Cassette, and it developed an intermittent fault whereby it just cut out. New speakers didn't help, and there was nothing obvious, no blown capacitors etc. Taking the cassette module out of the radio to look at the circuit board, I thought it was worth a try at leaving it out permanently, since I never play cassettes now, and it might be where the fault was... and the radio now works!

I sometimes believe such devices are intelligent and deliberately wind up their owners. Before I did the fix above, I bought a used radio on eBay, which turned out to need a code. The seller refunded me but didn't want it back, so I set out to read the code, which is stored in the main processor chip, using the instructions on Evilution's site. After much faffing with previously retired XP computers, a Chinese programming device, solder, adaptors, error messages, all taking many hours, I finally managed to read the code - just as I concluded that the original radio, as above, was now working! So now I have a spare.