Reading your comment, I thought either "nobody is going to believe this guy" or "people are going to think he's nuts". Actually, I thought it sooner than that, because I almost shared a story about how I used to clean up my Northgate Omnikey and decided not to because I didn't want to be judged. :) And yet, here you are, with an equally insane, similar but
much better approach.
My method for cleaning my Omnikey was to fill the kitchen sink with water and clean it like one cleans a dish. After a quick towel-dry, I'd toss it in the oven for 12-or-so hours at the lowest temperature (I think about 150-200 degrees American). I did this at least 10 times during the decade and a half that I used this board (and it was sold in perfect, working condition).
I'm sure I did some damage, somewhere. There's got to be parts in that keyboard that corrode, but it always came out "like new". I haven't owned a keyboard like it since and I expect the one I use day-to-day wouldn't survive a strong gust of wind. I'm not completely, nuts, though. The first time I performed this all-day, insane, cleaning routine was after I had lost all hope of resurrecting my keyboard due to an unfortunate encounter with a full glass of Mountain Dew.
At no point did I ever consider putting it in the dish washer. That would have saved me hours!