Since my new GS300 came back from having a new windscreen fitted (crack from a stone hit) the 'Auto' setting on the wipers hasn't worked properly. The wipers will run while the screen is dry, or fail to run when it rains - then start up and go on for too long or too fast. The sensitivity setting on the stalk control doesn't seem to make any difference. It all worked fine before.
I assume something has gone wrong with the sensor since the new screen was fitted. Before I go through the hassle of getting it back to the dealer to sort out, any ideas on checks I could try? It looks as though part of the sensor behind the rear view mirror might be removable (check for dirt, contacts, perhaps) but I don't want to risk making it worse (or screwing the guarantee!)
Jonathan