have an HP 1700. will HP boards that you have in stock # 4923,4924,& 4925 replace the ones in my piano.I have many dead keys.
We do not have the key contact boards that work in the HP-1700. Usually dead keys are the result of dirty (or worn out) rubber contact strips. So I would first try removing those, and washing them in warm water with dish soap. While they are off, you can clean the contact boards with rubbing alcohol - if there is any grit or anything on the contacts here, it can prevent the note from playing.
Once everything is dry, reassemble it - and hopefully there will be some improvements. If you still have dead notes, try swapping the rubber contact strip underneath those dead notes with one elsewhere on the keybed, and see if the dead notes now change position - if they do, the contact strip is the problem. If they stay in the same place, the contact board is the issue.