Nothing new, but I picked up this board for not a lot and really like it. I saw that Brutal posted a nice write up of his NEC APC H-412 restoration ( viewtopic.php?f=2&t=22609 ) just last month. I don't see much difference between the boards other than my H410 AT connector is beige and straight, rather than at a 90 deg angle. This board, too, was severely yellowed:
Fairly dirty once opened but not too bad:
I also went ahead and retrObrighted the case and keycaps. I also use 3% H2O2 nd have had good results with several boards. I used a glass baking pan with a Mylar emergency blanket under it as a reflector with two 90W halogen flood lamps and two CFL black lights over it. I tend to doubt the black lights really do much and suspect the flood lamps largely work due to how they heat the peroxide, but since this set-up works for me I didn't change it. I think the results were pretty good like Brutal's :
The alpha legends are may appear lighter than the dark keycaps. but at least on by board, that is because they are double shot grey and the dark keycaps are double shot black.
Also, although I tried to be careful removing the caps as recommend with the NEC ovals, I did pull the top off the F9 switch. Fortunately, it was easy to reassemble and the top retaining plate didn't break so I was able to just snap it back in place and the switch works fine. Part of the lower retaining plate is missing, but luckily hasn't caused a problem. So I agree - be careful with these switches!
My board works fine with an AT to PS2 adapter to Blue Cube (and the mouse/keyboard PS2/USB converter I got on Amazon now that the original Blue Cube seems to no longer be available):