In a recent repair to my 7-year old T430 which I reported separately I broke the connector off the keyboard ribbon cable which meant I had to replace the whole keyboard.  

I held the ribbon connector on both ends of the connector pinched between thumb and index finger and pulled upwards. I have removed the keyboard from this machine several times before without any problems.  

I would appreciate advice on how to avoid this problem if I ever need to remove the keyboard again.

Under the ram cover, there will be two screws. Remove them and flip over the laptop. Push the keyboard by the arrow. Then lift up the keyboard and remove the keyboard cable. That's it.

Thanks for the suggestion but it's precisely the "remove the keyboard cable" step that I'm asking about.

To answer my own question I see that in the following video the technician levers up one end of the connector using a metal screwdriver. Is this the recommended technique?

That works but I prefer something like a hard, plastic guitar pick which is less likely to leave any scratches

Thanks for the comment about using a plastic rather than metal lever. I am less concerned about scratches than about damage to the connector components. 

I was assuming that the keyboard connector plug and socket are designed for straight vertical movement rather than the diagonal movement which would result from levering up one end. 

I am also unclear whether the connector is designed for force to be applied to the ribbon cable or to the plastic backing plate on the socket.

If I knew the technical name for this connector I could perhaps get clarity from the design specification standard. Perhaps Lenovo design/engineering could supply this information?

Thanks for this clear advice.