I hate to say this, but i cant help but feel that "everyone" should return their units to have them fixed. The Amiga might be immortal, but we aren't. Sooner or later these things will start changing hands, and at that point, having to guess if yours will be more or less finicky with what drives it accepts...
That said, i understand why Jens isn't promoting this idea. He doesn't hold any obligations against a second hand buyer down the line, and lets face it, all he cares about is first hand costumers that are happy with their purchase.
I don't hold that against him, but i know if i had one, i'd send it in to get "fixed".
If nothing else, nobody knows for how long Jens will be able, and willing to provide the service, what do you do when your replacement drive isn't working?