update, so got the new relay shaft from veedubmachine, but they they were very poor at getting back to me via ebay...ended up ordering direct from their webite, which arrived quickly and had good communication.
When i come to fit the part, i decided to change the whole shaft, rather than just the ball. I then realised the shaft was supported via a plastic bush top and bottom, of which the bottom one had siezed to the shaft. I got one of these turned up at work, and then fitted that with the new shaft, the top plastic bush was ok.
So in summary veedubmachine are good, and if fitting a relay shaft complete be ready to replace the plastic bushes that support it.
Gear shift is slick now, thanks for all the advise.

186K valver and still going...
DD