Nearly exactly three years ago, I showed how to fix a common problem with the front wipers of the Renault Twingo (first generation). The cause is a spring for the ground contact which gets corroded/something and loses contact. The fix was to open the motor, cleaning the part and putting it back in again.
The fix didn’t last eternally, the spring will at some point lose contact again and you’re back to square one.
Luckily, Renault uses the same motor on different vehicles and that means, it has two plugs on it. The new fix, which hopefully will last as long as the car will, is to solder a wire onto the contacts for the second plug and attaching it to a screw holding the housing of the electric motor.
Here, you see where I soldered the cable onto the contact (the conductor is easy to trace on the inside – see this photo):
More detailed:
And here’s where I attached it. You can’t solder it onto the housing of the motor because of the paint and the other metal part is cast iron, so no luck there either. But luckily, the screw is perfectly placed.
Heshsum 
