Mine had no problem starting, but the wipers stopped anywhere they liked.
I took the mechanism off, took the cam housing apart (drilled the 'rivets' out), and cleaned the steel cam with fine emery (even though it looked clean, it was no good electrically). Drilled and tapped where the rivets were and reassembled- it's been absolutely fine since. Shouldn't take more than 2 to 3 hours, even if you've not taken one out before.