After buying another VIC-20, and getting the same results, and putting both computers away again, I think I finally found the problem last weekend.
I had thought that I had had extremely bad luck, getting two bad VIC-20s, with a fault that couldn't be easily diagnosed. I suspected that the LM counter chips (?) close to the serial port had been damaged. But then a friend (the one in the last message) brought his new VIC-20 to our Amiga club to play some games. His didn't work with the disk drive either!
Somehow, I forget how, we came to the conclusion that the serial cable was too long (3 metres or so), so we made a new, shorter cable (circa 1 metre). And it worked!
The morale of all this is, that the driver chips in the VIC-20 probably are weaker than in the C64.
1541 won't work with VIC-20
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