A while back I bought a non-working Akai MPK25 for the huge price of $70 with 3 keys not working correctly (assumed dirt or carbon) after trying a Carbon Contact repair, which did not work, I tested all the diodes and contacts on the board, there were some issues here and the only solution was a replacement Keybed. Unfortunately the AKAI replacement part is $110 + shipping so I went looking for alternatives rather than spend $180 on a S/H MPK which would be insane !
On the Akai forum someone had mentioned the Midiplus Origin 25 has a direct replacement board (OEM M-AudioOxygen Mk1 I believe) also made by TaHorng in Taiwan.
Now MPk's tend to have 2 main issues with the keyboard, firstly on the keys the plastic retainers breaking and then the Keybed Carbon wearing out (repair kits are expensive and messy).
So if you experience either of these issues this might be for you.
So I hunted on Amazon and found what looked exactly the same as the Origin25 - the "Badaxx" OR25 ... arrived today and lo and behold the entire keyboard fits right in, the keys, while the don't feel quite as good as the Akai, are a direct replacement also (and over $5 a piece for replacements!)
However the Badaxx does not have aftertouch, so installed just the circuit board of the Badaxxinto my Akai rather than the entire keyboard area and it works perfectly.
Also have an entire key set as replacements now for the future
The Badaxx keyboard is currently listed at only $44 So there you go - cheap repair for your Akai MPK 25