Weird. I fitted some PIAA silicon wipers last week. I have to recommend them, they work a treat. Water just beads off the windscreen and wipes clean with a single pass of the wipers. However, part of the fitting procedure is to run them dry for 5 minutes to get the silicon to coat the glass. After I did this, something happened - the wipers only worked on the high speed setting - intermittent and normal speeds did absolutely nothing. I thought maybe the brushes had burned out - I couldn't think of anything else it could be, apart from a fuse, and all were ok. I even ordered a replacement wiper motor.
But today...
I washed the car and gave the engine bay a thorough clean, and what do you know, when I took it for a spin this evening, the wipers were working again!
That has to be the easiest repair I've ever done!
Maybe there was a poor contact somehwere which failed under the strain of running the wipers dry. Perhaps I put pressure on the loom or a connector block somewhere and got things connected again.
Soap and water. Can't beat it.