After visiting (just now) the Alesis Fusion Facebook page, found out 2 very helpful new bits there.
There is a sale on the 128MB memory modules-too late for me I've upgraded both 8HD's already, 50 bucks apiece.
Even more importantly, on that thread appeared-Bob Schmanski-the tech who signed off on many technical aspects of our Fusions, one of the primary techs who still knows about these I would think, and apparently still has some interest in these, wow!
I had been trying to get contact info for him for quite some time, and there it was. I left him a message on Facebook re the elusive "service key" explaining why I was trying to find one-and will check back to see if he responds. also left this group's link on my facebook post. I don't usually frequent Facebook, but if he can't help, i will give up.
I am also thinking-since this serial number prompt only showed up in one of my Fusions after trying installs on both-I am wondering if InMusic sent me a 1) mainboard for a 6HD and thus possibly a mismatch-there may be subtle differences OR...2) the firmware which I have guessed is burned into a ROM looks for a matching serial number and since there were different generations of bootup firmware-not the OS files which are seemingly separate-when it sees a mismatch from the original mainboard-it throws the incorrect serial number prompt, although I have no idea where the boot firmware serial number would be other than the mainboard and thus how would it detect a mismatch, so that can't be right, maybe Bob will know.
I also asked him about the possibility of having partially defective mainboards repaired-since these are so scarce, and as a vital part, I felt it worthwhile to least ask. I have 2 mainboards like this, with probably minor problems beyond my ability to repair. Seems such a waste a part so technically advanced can't be salvaged, especially considering a replacement runs over 300 dollars US, if you can get one that works!