Check that the ribbon is square in its slot and that the clip is seated tight. Never pull the ribbon out with the clip latched. Always retract the latch before extracting the ribbon. I have a similar problem with an Escom machine I have but its kinda my fault as I don't have the top case screwed down and the keyboard moves around a bit. But if the ribbon moves out of square I lose various keys and the space bar often. Just reseating it fixes the issue. Worth a shot. Also cleaning the connector may help but don't abrade or cut or scratch the surface. Also remember which way you took the clip off cus if fitted the wrong way will render the keyboard dumb.
