I'm looking for sale or swap. I have a bunch of Master Compacts spare here and none of them have the keyboard encoder. And I've just checked online, and the BBC B's appear to use the VIAs, which I assume must be what's happening on the Compacts.
If I unplug the keyboard and turn it on, it starts, then i can plug in and type a few things before it starts printing too many characters then hangs. I've tried other keyboards and resoldering bits to no avail. I think it's the encoder.