Need 800 keyboard. Anyone have one for sale?

My brother's 800, he bought it in 1983, has died.  It's a late production 48K 800 with the Mitsumi keyboard. This is the same type Mitsumi keyboard that was made for the 1200XL, but for the 800.  I first thought that it was a similar issue shared by the 1200XL, but not one key works?????  Could not one good key possibly mean something else?  Does anyone have a very good condition 800 keyboard (preferably Mitsumi) they want to sell?

Also, could I take the circuit board and ribbon cable off a Stack Pole and put it on a Mitsumi set of keys?  I'm asking will the screws and connections line up?

Help!