Try cleaning the heads of the drive. My old 3k did the same thing. Turns out, it was 'cos the heads were out of alignment.
You should also try swapping your 2k's ribbon cable with the 3k's. I'm not saying it will work, but it's worth a shot.
Another thing to try, if it's possible (I'm not sure off-hand), but test the 3k drive in your 2k. If it doesn't work, odds are, it's toast. :-(
