Driving along at a nice 70 + mph when it decided to pour down switched on the wipers and they decided to stop mid sweep, turned out that the nylon/plastic ball joint had dropped off the motor arm spindle. Unable to get a replacement wiper rack (ball joint and spindle worn) so had to carry out temp repair by drilling the centre spindle and fixing with a self tapper and large washer. It seems that this could be a common defect and may be prevented by lubricating the wiper linkage ball joints on a regular basis (remove and pack with grease) even though nylon/plastic is supposed to be self lubricating.

I noticed that you can get 'repair clips' on eBay which hold the sockets together. Technically they are a temporary repair but apparently they can last for years.

Thanks for that, just ordered one at £5.38, the ball joints that fit the arm spindles are OK just the one attached to the motor arm is knacked.