V reg Daf 45 - wipers intermitantly not turning off?

Intermitantly when turning wipers off on stalk they stay on intermitant and you have to turn them back on again to either slow or fast and off again. sometimes they turn off, sometimes they stay on intermitant.
The wiper motor has been replaced due to a different fault, i have stripped the stalk down and cant see a problem.
Could it be the relay, or is it more likely to be the wiper stalk, or are there any other possible problems?

Many Thanks