YAY! It worked !! Just as shown in Woody’s video I was able to open it up, find the broken piece - exactly as his was - and glued it into place.
Really pleased as this was annoying me. Thanks again for everyone’s comments and links.
By the amount of similar posts, this is obviously a production fault which hopefully has been fixed in KEYLAB II keyboards ??
I noticed a lot of comments about looking for glue remnants when people are looking to buy a second hand KEYLAB like mine, and I found that whilst dismantling it, the weights used under the keys are actually glued into place, and many have remnants of glue all over them. Not therefore a sign that broken keys have been fixed, just messy manufacturing. I remember mine when brand new had some fine strings of visible glue underneath the key bed. For what it’s worth.....