Have you tried the floss mod on the model M? I'm kinda playing around with that right now. I have my home row flossed and the rest left alone. There is a huge difference. The flossed key don't feel any different, but they sure are a lot queter. If flossing isn't enough you can also try the rubber o ring around the spring well too. That will help quiet the keys as the bottom out. I have heard that by using the o-ring that key feel is changed, so you might want to experiment. Ripster has guides in the Modification forums here on GH. If I have learned anything at all, it's that I trust Ripster's advice when it comes to modifying model M's and Unicomp keyboards.
After my model M made it into the office I floss modded it. It's different, but still sounds like a machine gun. It is a 1993 1397599 with blue logo but there's no sign of the word "Lexmark" on it anywhere. The ENTER key has a pronounced WHACK when it bottoms out but the rest of the noise is mostly key release twang. It has the usual BS click, but what really makes it carry is the twang.
I wrote in another thread (my 'help my narrow', I think) that I also found a 3151 terminal 1392595 in my basement. It's an earlier black logo keyboard and although I no longer had them side by side, the 1392595 sounds tighter, quieter, and way less twangy. I'd also say that the BS feedback is also lighter. In that thread some suggested that maybe I have some broken rivets or something in the 1397599 contributing to the twangy racket. I have yet to purchase a low profile 7/32" socket to take it apart and see. It's really minty looking - no shiny keys, no scratches, not a hint of yellowing. I don't think it's seen a hard life. It's just really, really noisy. I was also thinking of trying to swap the 1392595 mechanicals into the 1397599 case, controller and keycaps to blend the best of both worlds.
I have not come across a thread where anyone has generalized that Lexmark versions are twangy while IBM versions are quiet, or anything like that. Just general statements of Lexmark being inferior, but only slightly, with no specifics... The closest thing I found was
here. The author seems unsure if he's just imagining things but he does describe his 1397599 to be stiffer and more twangy than his 1391401 but the difference could be wear, fiction, or who knows what. I suppose I could second that review and indicate that my 1397599 is twangy too. Is that because it's Lexmark? Or is there something different about the 1397599 design altogether? It's a much less popular model#. The only thing I see different about it is that "Alt" is in green on the caps.
Clickykeyboards has one for sale
here which seems to indicate that IBM made 1397599s too, and that the only diff is the green Alt and grey numpad labels. (
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