Just had my wipers go belly up on my 58 plate tourer. Stopped completely on mine turned out to be the right hand motor. Removed both motors opened the back found right one had let water in. Replace with a 2nd hand unit for £70 as new ones came in at £250. You might get lucky if you open it up and find its wet and dry it out and reseal. Since yours are both kind of working but id budget to replace at-least 1