Good morning

Well, this morning it's rainy here in Virginia and, initially, I used the intermittent setting on my wipers. All was good.
When I went to switch the setting to a constant wipe, the stalk would not click into either the normal or fast settings position. It worked normally with me holding the stalk in position but as soon as I let go in went to the intermittent position. It all worked fine the last time I used it. I don't remember hitting it or jarring it in any way when getting in/out of the vehicle.

I've searched the XK8 and all other forums on the website. Nothing.
Ideas?

Nick