Get ready for a nightmare. I actually just finished repairing one of these two days ago and I've had it for two years. When I received it it was pristine on the outside, possibly unused. It had bad capacitors and some blackened traces on the key matrix though, so even after replacing the caps it ended up being a complete nightmare to fix. I left it alone for two years after wasting several hours trying to fix it with winshield defogger repair epoxy (conductive paint basically). Most of the time spent is the disassembly and reassembly. All keycaps have to be removed before you take the keyboard apart. DO THIS FIRST, no matter what you picture in your head... there are no shortcuts here. If you leave the caps on, the second you unscrew the back all of the springs will pop up out of their housings and you'll have to manually set 101 springs back into their holders. It is very tedious and has to be done with the keyboard perched precariously on its edges to allow the springs to stay in place... if it slips down, they'll all shoot out of the housings again. You absolutely must take the key caps off, then disassemble the keyboard upside down with the springs elevated, separate all of the clips set into holes in the back and then remove the back without jostling the springs loose, or you'll have even more work to do. Realistcally, you should just plan on having to reset all of the springs anyway because its inevitable that you'll knock most or all of them loose...
The holder for the PCB inside is also an absolute garbage design and involves a series of plastic clips that were clearly only ever intended to hold the PCB in, not to have it removed. It is very hard to not break one. I had one break and had to replace it with a screw (thankfully there is a screw hole in the PCB in an area close to where the clip broke, and there isn't anything below it). This is absolutely essential because the PCB squashes down onto the contacts of the key matrix, and if there isn't enough pressure (due to broken clips) you'll have whole parts of the keyboard that don't work. I actually found that replacing the original screws on the back (only TWO screws holding this thing together... how cheap can they get??) with slightly longer pointed screws allowed me to tighten it together better which made it more reliable after all of my repairs were complete.
Anyway, the keyboard has the perfect layout, a great classic noisy-mechanical feel and sound, but is really really cheaply built and designed poorly. I can only hope that the repairs I did to the matrix all hold up. I used copper foil tape and defogger repair paint. I sincerely hope yours doesn't have damaged traces. Make 100% sure you use good caps and install them properly.
... have fun! 🙁
Now for some blitting from the back buffer.
