In the last month or so,the rear wiper on my 2013 facelift E class estate has started to have a mind of it's own. If I use the wash wipe or simply turn it on and off to clear overnight water,it stays on for roughly 5 minutes,pausing halfway between full strokes. Is this anything that anyone has experience of? A brief search of the internet suggests maybe the motor is full of carbon dust and is making it's own complete circuit through the dust/grease gunk inside? It brings up no codes on my Icarsoft MBII. Many thanks folks.