This happened to me with a Duo 280c that I placed a Revision F keyboard in. The keyboard worked fine in a 2300c, but not in that 280c. So I went back to the original 280c keyboard, which improved with use.
The 280c later died (it now will not spin up a HD), so it went in the "to be fixed one day" box and the keyboard anomaly is no longer what you could call concerning. But it seemed to me then and now, in your case, to be most likely keyboard ribbon related.
The 280c later died (it now will not spin up a HD), so it went in the "to be fixed one day" box and the keyboard anomaly is no longer what you could call concerning. But it seemed to me then and now, in your case, to be most likely keyboard ribbon related.